This needed to happen last year. Two botched years, and an offseason that almost turned disastrous with Malkin and Letang until FSG stepped in. Hextall had no vision for this team and was content to watch the slow decline instead of going for it with the few years we had left of one of the best cores in NHL history.
Guys like Rust, Jarry, Granlund et al, need to be off this roster. Completely retool the team around core three plus Guentzel. Everyone else can and should be considered expendable, there were way too many passengers this season as there have been since 2018.
Sullivan will not be picking the GM. I expect FSG to hire great managers who will mold the team according to their vision, and that includes the coaching staff, even if FSG loves Sullivan. I would not have been disappointed to see Sullivan move on, but I'm not bothered by him staying. I don't like any coaches that are currently available.