LeBron is keeping the East afloat. If he moves over interest in the Eastern Conference will be minimal. James, Davis, Durant, Harden, Curry, Leonard, Paul etc all in one conference will really fuck things up.
I think the opposite. If he shifts West, expect the Eastern teams to suddenly become very attractive for players.
Certainly the likes of Philly, Chicago, New York, and Boston, will become must see on the checklist for wantaway stars and free agents.
And instead of building teams to beat LeBron, as has been the case for almost a decade, they can focus on building winning teams.
I don't see him joining Philly, don't think they mesh with his style, his personality, or at at the level to offer him greater success than where he currently is. One injury to Embiid nd it's suddenly becomes another team to carry. Additionally, Simmons is a horrific shooter, hardly the type to thrive alongside LeBron.
Unless he can swing a trade to Boston, I think he'll either shift to LA with possibly George and another star, or potentially the Rockets if Paul takes a cut, Having said that, Lebron, Paul, and Harden, on the same team seems way too many dominant ball players on one team.