If some protestant individual feel that Catholicism suits him/her better, then he should do it, i guess. But I don't believe big groups of people would accept it, because they already built identity on Protestant churches and it is part of their culture now.
But generally watched, it's all Christianity, and i don't understand why differences between churches are so important today when they are minor. Who actually care about it and why?
And, as i said many times, faith and religion should be thing of soul and nothing else. I feel it wrong to say to someone in what he should believe or what to follow.