What do you mean? All four of them will be free agents next summer and the Spurs are projected to have massive cap space available (with an elite player already on the roster). I would say it's far more likely that all four of them take a discounted rate together (similar to the way LeBron, Wade, and Bosh did in Miami) as opposed to Harden, Paul, and Melo being maxed out (which is why CP3 and Melo want(ed) trades so that they can retain the option for that fifth year) and LeBron and Wade signing for the minimum. Sorry, nothing that Wade or LeBron has EVER done would lead anyone to believe that they would be willing to do that.
Regardless, it's all a moot point anyway since it's not happening with either team.