Well, you won't like this report from CBS:
http://cbsprt.co/1GjJU5Q
If his goal is lots of minutes, I assume he'd play C and backup PF behind Giles. Would be competing with Jeter at C, as well as any 2016 recruits like Bolden.
Were I him I'd look elsewhere for major minutes, but would love to have him at Duke.
In 2016-17, Duke likely starts (assuming they get Giles and Jackson to go with Tatum):
G Thornton
G Jackson- K loves two PGs.
G Jones- K loves Seniors with starting experience.
F Tatum- K loves a 4 with perimeter skills (Battier, Singler, Parker, Winslow)
F Giles- starts no matter where he goes.
So Nichols is the top backup inside, if he goes to Duke. Allen is the perimeter backup. Kennard and Jeter ride the pine as Sophomores. Obi is either buried on the bench or transfers.
K won't platoon, so the top 7 are the only ones that will see minutes worth mentioning.
If Nichols is serious about improving his draft status, playing behind Giles is not his best option, but he may not care about that and may just want to play at Duke.
Not a great business decision, but maybe there are other factors to consider.