I have to be quite honest and say that, in human terms, I do not see there ever being a unified Continuing Anglican Church mainly because of the lack of agreement about what constitutes Anglicanism. This problem actually predates the emergence of Continuing Anglican in the 1960s and 70s, and probably goes back a century before that to when the "Rits" and the "Rats" were fighting for inclusion within the Anglican and Episcopal Churches.
Prior to 1833 there was pretty broad agreement as to the doctrinal position of the Church of England and its descendents. Anglicans were, to borrow a phrase from Lutheran historiography "Evangelical Catholics." The Evangelical party placed emphasis, obviously, on the Evangelical side of that inheritance, and the "High Church" party on the Catholic. The old Low Churchmen, the Latitudinarians, were really concensus protestants who, for political and theological reason chose ot to push Anglican distinctiveness and represented the main challenge to orthodoxy, but since the 1760s they had slowly declined into insignificance.
The real fun starts in the 1850s and 60s when the Ritualists and Liberals start to gain a following. The early Ritualists were, for the most part, traditional High Churchmen who wished to revive disused ceremonies. They had not yet developed the "advanced" notions of full-blown Anglo-Papalism which copied post-reformation Roman Catholic devotions to "tart up" the rather dowdy reality of Anglican worship.
On the other hand, the Victorian Liberal was an optimistic beast who believed that religion could be made scientific provided rigid adherence to the old Orthodoxies were not insisted upon. Chief among the leaders of Victorian Liberalism was Arthur Penrhyn Stanley, Dean of Westminster in the 1860s and 70s, who believed that in order to be credible, Anglicanism had to slough off superstition and outmoded orthodoxies, and embrace a sort of religious Darwinism. Dean Stanley was also aware of the fact that the "superstition" of Ritualism could be used as a Trojan Horse to encourage Parliament to loosen the terms of subscription so that Liberalism could grow within the Church.
Stanley's "sotto voce" campaigning among the political elite achieved its aim in 1871 with the so-called "Shortened Services Act." This made some inconsequential changes to the 1662 BCP, but also went along with a measure that loosened the terms of subscription. Before 1871, ordinands had to subscribe that the Articles as being "agreeable to Scripture" i.e. that the Articles of Religion reflected Biblical Christianity. After 1871, ordinands were required only to "affirm" that they contain nothing contrary to Holy Scripture. This loosening of the terms of subscription was a far more effective way of undermining the authority of the Thirty-nine Articles than the tortured logic of John Henry Newman's Tract XC, and the looser terms of subscription did indeed make the Church safe for Liberalism.
One paradoxical result of this loosening of the terms of subscription was that as Ritualism morphed into modern Anglo-Catholicism. The extremists began to abandon the traditional Anglican standards of the Book of Common Prayer and the Articles of Religion. The BCP was overlaid with devotions imported from contemporary Roman Catholic practice, and the XXXIX Articles were increasingly seen as "an historical document" that could be largely disgarded, except as a civil requirement for those being ordained. The Bishops pretty much blew their chance of containing Anglo-Catholic disobedience to the Canons of the Church of England by going along with Disraeli's "Public Worship Regulation Act, 1873." This attempted to strangle Ritualism by legal means, but its major flaw was that it set up a semi-secular court to adjudicate ritual cases. This gave the Ritualists, who stood for their own peculiar version of the separation of Church and State, the perfect excuse for ignoring the new Court. The new court, which replaced the Judicial Committee of the Privy Council was seen as a seculiar court that was meddling in affairs beyond its competence. Unfortunately, so far as ritual (more accurately, ceremonial) matters were concerned, that level of competence was pretty low. The new court even managed to reverse some of the decisions of the Judicial Committee had made on the basis of the Ornaments Rubric, and Caroline practice. Prior to 1867, the Judicial Committee as successor to the old Court of Delegates had been pretty successful in keeping the liturgical peace if only because the Ritualists recognized that it was a Church Court of sorts. Two or three bishops usually served on the Judicial Committee when ecclesiastical cases came up, so they could not dismiss it as a mere secular tribunal. The worst result of the Public Worship Regulation was that it made "white martyrs" out of Ritualist priests who would rather go to prison for contempt of court than give up their ceremonial. As a result, this attempt at governmental enforcement of ecclesiastical discipline broke down entirely. Needless to say, a good deal of liturgical chaos followed.
Eventually, Archbishop E. W. Benson stepped in and used his authority as Primate of All England to take one particularly controversial case - that against the Bishop of Lincoln, Edward King - into his own jurisdiction. Benson's decision was to put an end to the use of the Pubic Worship Regulation Act. The PWR Act was quietly repealed a few years later, but by then it was impossible to repair the damage done to ecclesiastical discipline. However, Archbishop Benson's methodology had proved correct. Anglo-Catholics might question his decision, but they could not, without betraying their own principles deny his authority to make it.
In the end, Benson's judgement was all but an acquital for the Bishop of Lincoln, but it came too late to prevent the radicalization of the Anglo-Catholic movement. By the 1920s, Anglo-Catholicism had embarked on a programme to remodel the Church of England. Bishop Frank Weston called on his fellow Anglo-Catholics to "fight for their Tabernacles" but a more sinister development was the gradual replacement of the official Book of Common Prayer by the English Missal, and the Anglo-Papalist parishes where children were taught the 'Penny Catechism' not the Catechism of the Church of England. To many moderate churchmen, Anglo-Papalism was the cuckoo in the nest, but ecclesiastical discipline had so thoroughly broken down that there was little the bishops could do except boycott disobedient parishes and grumble about those priests under their authority who were "more Roman than the Pope." The Anglo-Papalist priest who said his Mass in Latin, ignored his Bishop, and tried to be as Roman as possible often had his bacon saved by a church patronage system that allowed laymen to appoint parish priests of their own choosing. This gave them considerable protection for episcopal attempts at discipline.
The PECUSA had nowhere near the same problems with Ritualism as the Church of England. Being an unestablished Church, American Anglo-Catholics could not argue that PECUSA's ecclesiastical courts were "secular tribunals" with no authority in church disciple, and after 1885, having seen severalattempts at placing Canonical restrictions on ceremonial fail. The Bishops then seem to have adopted a policy of trying to kill Anglo-Catholicism with kindness. Only the worst offenders ever got into trouble with the Bishops, and sometimes, when faced with Anglo-Catholic disobedience, the bishops would turn a blind eye, or seek to find a compromise. Generally speaking, even though Anglo-Catholics did occasionally feel they got a raw deal from their bishops, there was nowhere near the level of acrimony there had been in England. The Episcopal system of parishes electing their Rectors, rather than having them appointed by the Bishop or a Lay Patron as was the case in England, also served to damp down controversy. It was only when a parish unsuspectingly called a Ritualist that there was a "flare up."
However, American Anglo-Catholicism still developed in a way that made it a church within the Church. Anglo-catholics supplemented the BCP with unofficial prayers and devotions. This process finally culminated in the production such unofficial liturgical books as the American Missal, the Anglican Missal (American Edition), and the Anglican Breviary. These came to supplant the official Book of Common Prayer in the more enthusiastically Anglo-Catholic parishes. American Anglo-Catholicism also increasingly ignored not just the XXXIX Articles, but much of the Anglican theological tradition. Francis Hall's "Dogmatic Theology" represents this progressive rejection of the Protestant tradition in Anglicanism, and presents Anglican theology as being a species of Old Catholicism in which the achievements of the Reformers are often damned with faint praise.
Predictably, when the wheels fell off the Episcopal Church's Wagon in the radical sixties there were two differing versions of conservative Anglicanism looking for a way to perpetuate themselves. Both could agree on the centrality of Scripture, the three Creeds, and the Early Fathers and Councils, but were at odds about the degree to which the Reformation tradition should be perpetuated. One group, believing that the Elizabethan Settlement had failed, wanted to perpetuate traditional Anglo-Catholicism with only limited accomodation to those who were not prepare to go along with the whole programme. The other wished to perpetuate a pre-1960s Episcopalianism that would be mainly Central Churchmanship, but would encompass Anglo-Catholic and Evangelical minorities.
Sadly, after the St Louis Congress, these competing visions failed to coexist within the new church. Eventually schism resulted, and the situation was further complicatated by the existence of pre-1977 Continuing Anglican groups that had been largely ignored by the Fellowship of Concerned Churchmen at the time of the St Louis Congress.
Inspite of the fact that there are now six major and several dozen minor Continuing Anglican jurisdictions within the USA, there are only really two versions of Continuing Anglicanism. The first step to unit has to be getting all the jurisdiction that share "Vision A" together, and likewise all the churches that share vision "B." After that has been achieved we can then explore the potential for vision "A" and vision "B" to come together in one church. At the moment, we are wading through alphabet soup and not dealing the different visions that produced it in the first place. Too often in the past we have tried to ignore the theology and treat our Continuing Anglican divisions as being purely political. As a result, we have had even more divisions. So let's get real here. We need need to first get to grips with what we mean by Anglican and Anglicanism, and then deal with the political stuff.
In the final analysis it may well be that the two visions of what Continuing Anglicanism are indeed incompatible. If that proves to be the case, let us be honest, and have two continuing churches which love and respect one another, rather than attempt a forced marriage between ultimately incompatible visions.