I really hope Yukio can be a good guy, I like him. Personally, if they all could I'd be happy, but I know that shouldn't be feasible. Wait, this is Kubo we're talking about, so actually, it is feasible. XD
Yeah, I think him and Riruka are the more favourites of XCution. And yup, very few people die in Bleach (excluding Arrancar, obviously) - in fact, I wonder if Tsukishima and Ginjou will actually die, because, well, that's killing another person/human, as opposed to a Hollow.
With the Fullbring I guess it's a different story, as they started out as "friends". But since we don't know what Kubo has in mind for the coming arcs, it's difficult to speculate.
Don't forget, though, that Grimmjow isn't necessarily dead. He was slashed, we saw a panel of him grimacing, and that's it. And I'm still holding on to Ulquiorra's unusual death. Not to mention Nel and co.; we still don't know what's with them. If I remember right, Aaroniero, Grimmjow, Ulquiorra and Hallibel (though she doesn't count) were the only ones not killed by a Captain (though Aaroniero was killed by Rukia so...). Eh.
I think Ginjou, Tsukishima and the rest of XCution will be "dealt with" (whether that means killing them, turning them good, or letting them escape depends on what Kubo decides). Then Ginjou being a substitute Shinigami will be explained, and probably a flashback. Hopefully, more will be explained about Isshin and Urahara (though that's a bit of a stretch).
If I remember right, Kubo mentioned that after Aizen will be one short arc, and one long arc...?