My guess is that Danny Ferry recognizes that Smith is a "gone goose" (make that "hawk") and that Atlanta probably needs to blow it up.
If that's accurate, then I could see him taking Spur scraps like Bonner, Blair and Neal/DeColo/Patty (pick one) along with a pick or two. The picks would be the value.
I don't think the Spurs give up much more than that because Smith is the only person that seems to think he's a max player. He'd be a rental for this year's playoff push, looking for top dollar elsewhere this summer.