Manu will be a big part of the Spurs' future planning.
The Spurs had a relatively quiet off-season in which they simply re-signed their free agents and brought over Nando De Colo for a bargain price. Tim Duncan's contract, which was rumored to be similar to Garnett, was actually much smaller and Diaw, Mills and Green were re-signed to reasonable contracts. Now that the dust has settled, let's look at the Spurs salary commitments for this year and how things could shake up in the near future.
The Spurs have $69,242,481 in committed salary on the following players:
Tony Parker $12,500,000
Manu Ginobili $14,107,492
Stephen Jackson $10,060,000
Tiago Splitter $3,944,000
Matt Bonner $3,630,000
Kawhi Leonard $1,861,920
Cory Joseph $1,105,560
DeJuan Blair $1,054,000
Gary Neal $ 854,389
Danny Green $ 3,500,000
Nando De Colo $1,400,000
Patrick Mills $1,085,120
Boris Diaw $4,500,000
Tim Duncan $9,640,000
The luxury tax has been set at $70,307,000, which leaves the Spurs very, very close to crossing it and is the reason why Duncan signed for the amount he did: he got as much as the Spurs could offer without going over the luxury tax line.
With the exceptions all gone, minimum salary deals are the only ones the Spurs could offer, but signing someone would put the team dangerously close to the line (or above it). If someone like Diaw becomes available for the minimum after buy out season, I think they'd pull the trigger. Yet at this point, there aren't a lot of quality players out there willing to play for the minimum in the market, so I believe the Spurs will start training camp with the guys on the roster right now.
As far as trades go, being so close to the tax line hurts the Spurs' maneuverability. Tax payers can only trade for a player whose contract is 125% of the outgoing player plus $100,000. Non-tax payers have more flexibility since, depending how big the trade is, the CBA allows them to take on significantly more salary. Aside from the CBA restrictions, the Spurs seem committed to avoiding the tax, which means that they will be wary of any trade that adds salary. Going a million or less over the tax threshold is easily solvable; going a couple of million over would make it much harder to make a move to get back under the line.
One transaction that would provide the Spurs with some cap flexibility would be trading a player to a team under the cap for nothing more than a conditional pick, a stashed prospect or a trade exception. Unfortunately, doing it once the season starts could prove very challenging because of the salary cap floor. Teams are required to at least spend the equivalent to 85% of the salary cap, or $49.3 million. Most teams are already way over the minimum, which makes it hard find someone with space to absorb a sizable deal like, say, Matt Bonner's almost $4 million contract.
Basically, a salary-increasing move seems very, very unlikely unless there is another, cost-cutting move that goes with it. If an opportunity too good to pass up presents itself, I would assume the Spurs would move on it and figure out how to dodge the tax penalty later. Otherwise, the Spurs will probably not make a significant move that could put them over the tax line.
What happens after this upcoming season?
Next season, the Spurs will have around $38 million in committed salary, but will face some tough decisions with Splitter, Jackson, Blair, Neal and especially Ginobili becoming free agents. That cap space won't really be usable until the Spurs either re-sign or renounce those players, since Manu or Jackson's cap hold alone puts the Spurs over the cap. If the Spurs renounce all their free agents, they'll have enough money to offer someone a max deal but that's it. After that, only the room exception and veteran deals could be used to fill out the roster.
The only 2013 unrestricted free agents that are worth the max are Andrew Bynum and Chris Paul, and it's doubtful they'll leave their teams. Other than those two, Josh Smith and Al Jefferson will probably command near max salaries and Kevin Martin, Paul Millsap and Nikola Pekovic might get 8-figure contracts. Lamar Odom, J.J. Redick and Nick Young should get mid-level type deals. If there is a way to get two good pieces at positions of need, the Spurs should consider letting their free agents go. Otherwise, there's no realistic target that would be worth losing several solid players.
Blair's 2013/14 qualifying offer is low enough that, if he's not traded during the season, the Spurs might wait for the market to set his value and either re-sign him or not, according to their assessment. Splitter's QO is bigger and could be a road block in the re-signing process, if the Brazilian doesn't put together a good season. Having said that, if he doesn't regress or someone overpays for him, I'm pretty sure he will be re-signed. Neal will be a restricted FA but with Green, Parker, De Colo and potentially Joseph, Mills and/or Manu on board, it's unlikely that the Spurs re-sign him. In fact, I think there a pretty big chance he might be gone during the season via trade.
Jackson is an interesting case. The Spurs have his expiring contract to dangle in front of teams looking to cut back on long term commitments in a potential trade, but between the restrictive nature of the Spurs' own cap situation and Jackson's performance in the OKC series, the Spurs might decide to hang on to him for the year and let his contract expire. The problem is, in the summer of 2013, his cap hold would destroy any cap space the Spurs have. If Ginobili and one of Splitter or Blair are retained, the Spurs would be very close to being over the cap and re-signing Jackson would make sense, since it wouldn't impede other moves. Jackson's fate, more than anyone's depends on what the Spurs do with Manu.
As for Ginobili, I doubt the Spurs are willing to let him go unless his game falls off considerably this season. However, a long term commitment seems equally unlikely with Tony Parker's contract being only partially guaranteed in 2014/15 and Tim Duncan's possible retirement looming. Ideally, the Spurs would sign Ginobili to a sizable 1-year deal and keep the gang together for one more run. In the summer of 2014, the Spurs could only have Joseph, Leonard, Green's 4.5 million and a portion of Parker's partially guaranteed deal counting against the cap. That's when the Spurs could put together a brand new team. If Manu is re-signed to a 2-year deal (it seems more than likely) and Tim picks up his player option, in 2014/15 the Spurs would have the "Big Three", Danny Green's final year and the qualifying offers to Joseph and Leonard counting against the cap, with one of Blair and Splitter likely also in the fold.
As you see, the Spurs will have a lot of tough decisions to make starting this season. If they don't think Splitter and Blair are worth committing long term money to, they might decide to trade one or both of them for assets. With the guard depth they amassed, PATFO has made Neal redundant and it wouldn't be surprising if he is traded mid-season. Jackson's contract provides a good trade chip considering the more restricting tax that looms in the horizon, but the Spurs don't seem willing to go over the current line, which makes any trade that adds salary very unlikely. And then there's Manu. If he continues at the level he is now, Ginobili's next contract could be anywhere between $5 and $10 million a season; are the Spurs willing to spend that on a guy on the wrong side of 30?
Update: after double-checking Blair's status, prompted by some questions in the comments, I realized that DeJuan Blair will be an unrestricted free agent. That seriously increases the chances he gets traded. DeJuan has mentioned that he's not happy with his role on the team after seeing his minutes disappear in the playoffs for the second consecutive year and being shopped earlier in the off-season. Without the security that restricted free agency provides, the Spurs probably realize he will leave at the end of his current contract for either more money or a bigger role somewhere else and will try to get an asset for him before that happens.