If it's true that Bertans is coming over this summer, then the Spurs have 13 of 15 spots locked down, provided they bring back everyone except Bonner. If Matt comes back, then it's only 14. DeShaun Thomas seems -bent on staying on this side of the Atlantic next season, so the Spurs are probably have to give him a camp invite. In such a case, I see Thomas and Daye fighting it out for the 15th spot. If there's no Bonner, then they would probably both get a spot.
The only way I see a first-rounder getting playing time (or even a roster spot) next season is if at least one of Mills, Diaw, Baynes or Bonner fails to return. The problem is that the Spurs won't know any of that on Thursday. So they'd probably pick a stash player anticipating a tight roster.