In 2014 (latest year for which I can find stats) about 67,000 adults previously baptized were received into the US Catholic church. While a not unimpressive figure, this averages out to about four per US parish. So, unsurprisingly, leaving a former denomination for the Catholic church is a relatively rare decision, and I would guess that in the majority of cases it is done in the context of marrying a Catholic (a 2009 Pew Research study estimated that this was the deciding factor in 72% of conversions but this included both adult baptisms and receptions). There is no evidence that the establishment of the OCSP has had any impact on this larger statistical reality. Most adult church attenders are happy with their denominational experience, and if they're not, blaming it on the fact that perhaps their denomination is not part of the One True Church after all is not the first idea that pops into their head. Some will come to that conclusion, but they will always be a fraction of 1%. An ecclesial structure built on their membership will be necessarily a niche operation.Another visitor has suggested,
As to new groups, large numbers of communities tend to come in waves driven by "reforms" that make the denominations to which they belong no longer hospitable for them. The original wave that motivated the so-called "pastoral provision" was driven by the decision of the Episcopal Church -- U. S. A. (ECUSA), now known as The Episcopal Church (TEC), to ordain women. The more recent wave was driven by the TEC decision to promote a practicing homosexual to the office of bishop and push for sanction of homosexual unions in both TEC and the Anglican Church in Canada (ACC) in North America, and also by similar actions in the Church of England (CoE) and the Anglican Church in Australia. However, there are always a few outliers that petition between waves. These outliers may experience some local provocation (replacement of a supportive bishop with a bishop who is not supportive, for example) or no provocation at all.I think there are practical problems with the idea that there may be additional waves of Anglican defections. While the Gene Robinson wave led to creation of the ACNA, it doesn't seem like there has been any further equivalent wave following the endorsement of same-sex marriages. This may be because the fate of parishes that leave their denominations in prior waves has been conclusively and consistently demonstrated -- they mostly lose their properties and dissipate their resources. It's a destructive and counterproductive effort.
The second issue is that defections have mainly been from low-church parishes. This is particularly true of the ACNA, but among those familiar with the ACA, thought to be the highest of the "continuing" denominations, even it has generally proven to be low-church. This means that a disposition to leave TEC has not automatically meant a motivation to join the US-Canadian Ordinariate.
