This shows you have no clue about the Spurs. Leonard is already the starting 3. Leonard was going to get a lot of run regardless. S Jax is his primary back up. Both he and S Jax also put in some time at the 4 in small ball lineups, so though both can play the 2 this isn’t likely to greatly affect their usage.

The Spurs have a plethora of quality subs in the back court. Look for more Gary Neal and possibly some Nando de Colo, both play makers with the ball in their hands and more capable of replicating some of what Manu does for the second unit than Leonard or Jackson.