But, I'd rather see his flashbacks.
Seconded. It would be cooler to see what happened with the Blackrock - it would cover what we saw beginning in last season's finale.
History is the same up until 1977, then everything changes.
From all that we know so far, yes, the divergence should occur due to the bomb.
Unless - the bomb doesn't cause the divergence,and is only a vehicle for the Losties to jump forward to the current island time. In which case, the Losties might still jump backward to whatever time for whatever activity is the planned plot climax. But that way is just unknowable until the creators reveal all. So, I'll stick with the 1977 idea.
So I think at this point, we might see an old Richard Alpert in the flash-sideways (in case he no longer remains ageless from 1977 onwards). Or maybe he will accept to be the protector of the island. And then *he* can remain ageless. (Cos Jacob also doesn't seem to age).