If Harry does anything halfway similar, I don't think it'll be until the last book. I figure Harry might have some sort of near-death experience where he meets his parents or something and has to choose whether to live or die, which would be a *symbolic* death and rebirth, but I don't expect that until the very end.

I don't think Harry will go beyond the veil or anything like that. I think this is mostly a fanon misinterpretation of the "magical world" JKR said Harry would eventually visit. He may go to Jupiter or inside somebody's mind or in one of the various "fairylands" of Irish lore, but as JKR said that dead people stay dead, I can't imagine her breaking the rule.... even for Harry.

I also don't remember a comment about her supposedly not killing Sirius. I'm gonna have to go with the "urban legend" crowd about this one.