If Allen is back, Duke is really crowded next season. K only likes to play 7-8 guys. They would have 9 5-star fighting for minutes. Their lack of size puts Jeter in the mix.
Right now with Allen back, it looks like one of the guards will be riding the pine. Allen and Thornton probably start, with Jones getting lots of minutes as a Senior leader. That leaves Jackson and Kennard to battle for the last backcourt spot. Up front Tatum, Giles, Jefferson, and Jeter get the minutes. That's how I see it.
If Allen leaves, K has 8 guys just like he usually prefers it to be. Thornton and Jones start with Jackson and Kennard off the bench. Tatum at the 3, Giles at the 4, and Jefferson at the 5 with Jeter off the bench.
Or if K decides to go with a smaller lineup with a 3 man at the 4 spot to stretch the defense (which his 2000's championship teams all have- Battier, Singler, Winslow) he might start Thornton, Allen, Jones, Tatum, and Giles with Jackson and Kennard off the bench on the perimeter and Jefferson off the bench inside. Jeter would not play as much in that scenario, I wouldn't figure. That makes the most sense, because it opens up more minutes for the perimeter guys. If Allen isn't back, then it doesn't really matter.
That team looks scary good, but if they have a weakness on paper, to me it looks like the PG spot. Thornton is good, and will get better, but he doesn't look to be a championship caliber PG to me. He might be by this time next year, though. But right now that looks like their Achilles Heel, if they have one.