Why They Will Trade
I see the Spurs making a deal in one of two ways:
First, they could make a swap for a high-impact player, if they feel it necessary to be able to handle the tough seven game stretches against possible opponents OKC, LAC, and Miami. This kind of addition would most likely be a 4/5, potentially starting alongside Duncan and moving Splitter back to provide a Spark(le) off the bench. Al Jefferson's name has been floated recently, though I have serious doubts about his chances of wearing the Silver and Black, but either way, it would likely be a rental like him. Josh Smith or Pau Gasol are names that are perennially batted around the blogs. Paul Pierce could be moved. Tyreke Evans has been talked up. Oh, and Josh Childress is still out there, possibly pondering if maybe Europe wasn't so bad after all.
Second, if they decide their current roster is good enough or close to it, they could bring in a contributor, someone a la last year's Diaw who can make an immediate impact and shore up a potential weakness. Could we use an extra wing in case of injury to one or more of Green, Leonard, Manu, Neal, or Jackson? Maybe another big to give both Duncan and Splitter a break without having to rely on the Bonny Bunch of B+(being benevolent here) Big Boys (Blair/Bonner/Baynes)? Maybe a vet true point to spell Tony? Shawn Marion, and Vince Carter are names being talked about. I'd be real happy getting Timofey Mozgov from Denver if we at all could. Sam Dalembert will likely be traded, and you could say he's hot right now. Milwaukee could also move Beno Udrih, according to Brew Hoops. Wouldn't that be fun?
It definitely would, but I just don't see it happening. All those guys you mentioned would probably contribute (except Vince Carter. Shame on you), but I don't think the Spurs have the pieces to get them, especially not the true impact players. I'm not as convinced the Spurs need another point guard as others but I guess I could see them go after someone like Will Bynum or Luke Ridnour if the asking price is low enough. Blair is probably gone but what comes back might be closer to "conditional second rounder" than "playoff contributor."
What I think the Spurs might try to do is explore trading Stephen Jackson's expiring contract for a player that will surely be with them next season. Jackson wanted an extension, which means he wanted to be paid at least $8 million on his next contract. I'm assuming that's more than what the Spurs want to pay him. Letting his contract simply expire doesn't help the Spurs, since Manu Ginobili's cap hold alone will take up all the cap space the Spurs would have. Even if Manu re-signs for cheap the Spurs still have to re-sign Splitter. That leaves them with very little wiggle room in terms of improving the roster this upcoming off-season. By trading Jackson (and/or Bonner's partially guaranteed contract) now for a guy under contract next season they could secure a contributor for a couple more years.
This is not a Trade Machine post so I'll leave the details to R.C. but a guy like Amir Johnson should be solid value going forward and the Raptors might want to clear some room to re-sign Lowry. It would probably mean absorbing Linas Kleiza's contract, which would cap out the Spurs for next season, but the likelihood of the Spurs signing anyone better than Johnson using the MLE is not high. If the Wizards want to clear Ariza off their books, they might throw in someone like Vesely, Seraphin or Singleton. This type of move would, ideally, allow the Spurs to add an asset whitout seriously compromising their future. It's similar to what teams with cap space do: take on a little money short-term to add a good player. The chances of this happening probably hinge of how convinced the front office is about Jackson giving them a discount but it might be something to consider.
Why They Won't Trade
More likely is a scenario where the Spurs stand pat. They are once again on track to hold the league's best record at the end of the regular season. This time, however, the young-ish nucleus of Splitter/Leonard/Green/Neal is more seasoned and proven. They have looked pressure in the eye and, well, you know. How they perform against the best of the league in a championship series can't be predicted, of course, but logic says we will see an improvement over last year's Harden-induced meltdown against the Thunder. I'm doing a piece soon breaking down each legit title contender and how they match up with the Spurs, top to bottom. Suffice it to say, for now, that I actually believe we are as good or better than anyone, but we do have weaknesses that great teams will try to exploit.
I agree here: the Spurs probably know they are one of the few true championship contenders and will not make a move that could alter team chemistry and continuity just for the hell of it. There's a case to be made for trading some of the older role player and furthering the youth movement but the team just added Baynes and has stashed prospects developing in Europe. I doubt we see Hanga, Richards or Bertans make the jump anytime soon but the franchise has some talent waiting in the pipeline, so I don't see the Spurs shipping out Neal, Bonner or Jackson just to get younger. There will be a time to worry about the post-Duncan future but this isn't it--not when the team seems like a legit contender.
As you mentioned, the Spurs do have some weaknesses (can't wait for the detailed report) but then again so does everyone else. And the prospect of creating new holes by trying to plug others through a trade scares me. I'm usually not a fan of maintaining the status quo but when a team is as good as the Spurs are right now, staying the course and seeing where the chips fall might be the best way to go.