For Tre it is not a question of whether or not returning to school can help his draft stock in a big way, because it absolutely can. He could very easily go from the second round to mid-first, or even higher, with another year of development. For him I think it will come down to a few notions: did he come in 100% dead set on being a one-and-done, because if that is the case they rarely change their minds. Also, he came in as one part of a four-part collective, and the other three are 100% gone. Is he okay being the one still behind? I hope he doesn't exclusively look at it in that context, but it is a factor nonetheless.
I think there is a more than fair chance he comes back. I know it is hard to be optimistic because it seems that everyone always goes no matter what. Either way I wish him well, but boy it would be nice to see him in a Duke uniform again.