I really thought Kawhi and LMA were going to develop a killer high-low game by the end of the second year. They haven't - and you can't fault Kawhi, so there's only one place to look.
Kawhi IS the franchise, and you have to build a team around that. I don't hate LMA, but there's not a of a lot of chemistry/synergy between those two. I don't think the team has to move LMA because of age, but I do think that they have to put complementary pieces on the floor with Kawhi. Going with younger players means some time spend rebuilding. But I think it builds a better team in the long run.
So, yeah, I'd move him for the right package of younger players/picks.