Joel Embiid is just outright good. No way around it.
Jimmy Butler is a cancer. I don't think he can succeed in a team environment. His past performance demonstrates this.
Harris may stay, but if he does, he won't have the impact he could have elsewhere.
Ben Simmons will struggle every year in the playoffs until he develops some level of an outside shot. A good coach will dissect him. If they have a good backup, they could make it work, but even then... it would be difficult to manage using a starter with an ego like that in the playoffs.