I don't think we're being very serious yet. Let's really talk about Josh Smith scenarios.
1. Hawks, out of contention, trade Smith without a guarantee of extension.
The Hawks look like a playoff team to me, so I think that this is the least likely outcome. Still, injuries happen. In this scenario, the Hawks will take back whatever they can get of value from a contending team (or a desperate team who thinks it can resign him, or both). The Celtics would be in the mix, here, because they would expect to resign him.
Possibilties:
1a. Smith (and garbage?) to Celtics for some combination of Bass, Sullinger, Bradley, and picks.
1b. Smith to Denver (scary...) for some combination of Koufos, Mozgov, and Chandler. (Hawks want Faried. Nugs say no)
1c. Smith to Minnesota for Derrick Williams and JJ Barea/other
1d. Smith +filler to San Antonio for Kawhi Leonard and Stephen Jackson
2. Hawks extend-and-trade Smith or trade him to a team that he agrees to extend with
In this scenario, the Hawks might get more back. As far as I can tell, the suitors look similar to case (1). There are some interesting non-contenders who could get in on it, but this is tricky because it will take either some seriously valuable players on medium-sized contracts or some big expiring contracts to make it work.
2a. to Cleveland for some combination involving Varajao and Thompson/Waiters
2b. to New Orleans for some combination involving Ryan Anderson and Austin Rivers
2c. to Houston, for Kevin Martin's expiring deal and a rookie smorgasbord
2d. to Detroit, for Maggette and other expirings and either Drummond or Monroe
3. Smith takes the max/near-max offer of his choice in the off season
I think Smith will be too choosy to extend with any of the (2) options, and I think the Hawks will ride him as deep into the playoffs as they can. That leaves this as the most likely scenario. It's also the most boring. Ho hum. So, who has cap space?
3a. the Jazz, for whom Smith would be an upgrade over Jefferson or Millsap
3b. the Wiz...
3c. the Cavs...
3d. the Bobcats...
3e. the Pistons
3f. the Bucks
3g. the Rockets
3h. the Celtics if KG and PP both retire.
It looks to me like it's the Rockets or the Jazz, here. If Smith doesn't like these options, we're left to speculate about what kind of discount he's willing to take or what kinds of salary dump trades the 2013 off-season might hold. If you ask me, though, most likely scenario has him signing with the Rockets, where he and Jeremy Lin could make the foundation for a very good defensive team and a beautiful pick-and-roll. The Rockets also have so much cap room that they could potentially woo him by letting him pick another teammate.