Danielson won't return unless doctors give him the okay. He's received that okay already from a number of doctors, and is pursuing treatment. He's not a fool- if he does come back, I think he'll be conscious of the fact that he doesn't need to do the dives and headbutts and sick bumps. He has said he really admires guys like ZSJ and their style, so it's not difficult to picture him adopting an aggressive grappling style that doesn't rely on bumping quite so heavily. I mean, really, that's sort of what he did as ROH champion already.
Should he come back? I dunno, I'm not a doctor. I do think it's worth saying that there are few wrestlers who retired because they had a kid. Additionally, I think he'll have a better idea of exactly what he's capable of than any of us armchair quarterbacks.
Speaking as a big Bryan Danielson fan, if he does come back, I hope he does it on a non WWE stage and does what he thinks is cool. I think he was undervalued there (yes, yes, despite his Mania win), and I think he would mean a lot to a tentative NJPW looking for a big American arena show or just buoying US independent wrestling in general. The guy will be able to write his own ticket, no matter what he decides. I want him and his family to be happy, most of all, and if coming back does that, mazeltov. If not, I'm okay with that, too.