He's been rising in draft projections. Last mocks I've seen have him in the late first round, which is always a dangerous territory. Very easy to slip from first round gurateed money to second round (less money, no guarantee). I would rule him out coming back. Can make good money, get stronger and be better positioned in a weaker draft the following year.
If Luka returns, he will start over Powell. Personally, I hope we keep him (and Dixon and Stevenson). I believe in the benefit of continuity.
We will still need another banger inside. If Vasaar stays, that gives us flexibility position wise. If Vasaar leaves, it will need to be a 5.