Well, I think the worst case scenario for Sullinger is that he can do most of what Bass can do (hit the jumper, finish relatively open looks under the rim) and rebound a bit better. The question will be whether he can do the latter two skills as well as Bass can do them (which is darn well).
Best case is that he develops that post game and has the other skills, which would make him a very valuable player.
Time will tell.