Dunc'd On made a interesting point; The Spurs could simply offer him the designated player super max but instead of the full 35% max, have it be like 32%. If he doesn't return this season, then he'll probably be inclined to sign it and lock into guaranteed money that he wouldn't be able to make otherwise.
If Kawhi plays well next season and still wants to be moved then the Spurs could move him with 4 years remaining on his deal thus opening the field up to teams that wouldn't otherwise make a move for a disgruntled superstar for fear that he would sign elsewhere.
Teams with good assets and lack of top talent, such as Phoenix or Atlanta could enter the sweepstakes and drive up Kawhi's value by giving the Spurs various options.
On the other hand, if Kawhi and PATFO can repair their relationship and Kawhi returns to his 2016-2017 level then the Spurs will have locked up him up but at a pretty good discount.