I will be shocked if it's not UT, and I'd also be surprised if he doesn't already have a pretty good idea where he's going.
I think he likes Duke, dad and the rest of family like duke, but at the end of the day it's a bit further than he really wants to be.
I think he also likes Memphis, mom definitely does and I'm sure the family would like to have him that close to home. However, immediate playing time is something he's looking for and it's unlikely he'll be promised that at Memphis.
Tennessee really has no negative aspect to it in regards to what Austin and family has said is important to him. They're close enough to home that the family can make the trip for games. His twin sister who he's very close to is here and the family could "kill 2 birds with one stone" when visiting Knoxville. A lot of his very good friends are here at Tennessee as well, and he's really expressed interest in getting back to school with them. And maybe a couple of the most important factors...Martin has shown a committed interest in Nichols and made him a priority since he was hired at Tennessee, that doesn't always work, but we saw what it did with Hubbs. Tennessee also has a much more attractive opportunity for early playing time than Duke or Memphis, he basically has a guaranteed starting spot here next year.
Now he may pick Duke or Memphis, or maybe even Auburn, but as I said, from speaking with him and reading where other schools feel they are, I'd be shocked if he wasn't a volunteer next year.