Abner was in Last Crusade? I must have missed that part.
I don't think Young Indy should be in the new movie. It was a gimmick that worked because it added something new. Doing it again would just convince me that Lucas had run out of ideas.
Another possibility, which I'm not in favor of, is that the opening gambit could involve Indy's son, rather than Indy himself (assuming he has a son in the movie, though this has not been confirmed anywhere yet.)
Personally, I'd rather just see something along the lines of the opening gambit from Raiders. That remains the best one of all three openings so far.