I don't need to remind you of the disconnect between Catholic laity and their bishops, over birth control, over gay rights, and in their response to (and disgust about) child abuse. So in many ways, the ROman Catholic laity are closer to the mainline protestants (like you Episcopalians) while the Bishops are fighting the culture wars in alliance with Focus on the Family.
Moreover, while the institutions and leadership of the RC church go on trial for covering up child abuse, retracts its apologies, then seek to discipline the American nuns, but reinstates HOlocaust deniers, and also disciplines any theologians who disagree about women's ordination, the laity is leaving.
1 in 3 cradle Catholics will leave, and increasingly those who stay are disengaged from the Church. For every new Catholic who joins, three will leave.
So, as pointed out at the Lead, the interesting split in American Christianity may be already be occurring within the Roman Catholic church.
Still I think that the biggest force holding the American Catholics together is the strong sense of Catholic identity, the in-jokes of cultural commonality. For example:
Q: What's black and white and black and white and black and white?I grew up Roman Catholic, I was educated in Catholic schools, and that is the sort of cultural joke of my childhood. Catholics get it-- like jokes about the white smoke. Of course, that Catholic identity wasn't enough to keep me in the Church, but it did prove a real barrier for BP to leave. And I think it's a big barrier to our many RC friends, who have that sense of belonging and are able to overlook the more egregious attacks because they aren't affected personally. So they go on ignoring strictures against birth control, and don't actively oppose marriage equality, and since their parish didn't have any child abuse scandals they ignore that too, and so maintain their cultural identity.
A: A nun rolling down a hill.
Still, while their kids and grandchildren will probably identify as cultural Catholic, they probably won't go to church, and will struggle to find that same sense of community, of purpose, and of meaning.