Well, here's a major argument-starter. Peter Leithart in First Things argues that Protestantism is over, that Protestants should stop calling themselves Protestants and call themselves "Reformational catholics" instead.

I sympathize, and of course speaking as a Catholic I think it's a step in the right direction, but:

Like a Protestant, a Reformational catholic rejects papal claims, refuses to venerate the Host, and doesn’t pray to Mary or the saints....

In short, this Reformational catholic will adopt a certain number of Catholic beliefs and practices, but continue to reject certain crucial ones (refusal to venerate the Host implies disbelief in the Real Presence), most crucially the authority of the Church. He doesn't say so explictly, but it's an obvious corollary.

This makes me think of a Chesterton observation about Protestants adopting Catholic practices: that, like shipwrecked mariners, they are always going back to the wreck for something. I'm afraid Leithart is only edging toward the same untenable position that Anglo-Catholics have occupied for so long.