spoilers:end of spoilers
I would assume Hal actually will have a much larger role to play considering that Parallax Hal from Zero Hour is involved with the Crisis energy they need to cause an anti-crisis. Not sure if they can just get that from Hal directly or if it will have to be gotten from Dark Multiverse Parallax or whatever. Probably doesn't hurt that Hal also had a recent run in with multiverse stuff in Morrison's Green Lantern and Black Stars.