I don't think there's anyway Philly will pay both Harris and Butler, given that Simmons will be up for a max contract soon. If they were smart, they'd keep Harris and let Butler go to the Knicks or Lakers or whoever. He's a destroyer of locker rooms, and Harris is an all around good guy who gives them a better outside shooter than Butler, something they need with Simmons at the point.
IMO, Kawhi is gone to the Clippers as soon as he can.