Don't see any possible way Atlanta wastes that first rounder on an expiring Brandon Bass. Trading away Payne for a first rounder makes all the sense in the world for Atlanta. Trading away that first rounder for a guy who could walk in a couple of months makes considerably less sense.
I don't either. That said, Brand for Bass works straight up, so if that's an improvement to the frontcourt Atlanta wants to make, it can happen easily from a salary perspective, and the only negotiating would be regarding draft compensation. While I'm sure some will speculate that the roster spot is for a free agent (like Allen), they can always release someone else at their bench, like Muscala, to make room for him. Also, Atlanta still has its room exception, and so can offer Allen, or any other free agent, more money than most of his other suitors.