He's a lot of things but he's not stupid. He finally figured out the winning formula and that's for him to let the experts do their jobs.
And he also has a new arena, basically, and for a brand new shiny training facility.
He has to know this is the last time people are buying what he's selling. If he goes back on his word then the city will turn on him entirely, players won't play for him, and the league might not be able to sit idly by while he ruins a franchise that has just proven its worth.
This playoff run helped in showing everyone in the country how great of a basketball city Phoenix is. I can't see Sarver getting away with the same things he did late in the Nash years nowadays with social media as prevalent as its become.