Embiid has to prove he's able to play at all before he worries about playing starters minutes breh
If in those limited minutes he shows that he can handle more minutes and he's playing lights out, then you can decide who you trade out of him and Jahlil.
They're going to trade the one with no injury history

Jah is already younger and ahead of him in development, ontop of not having an repaired foot. Honestly, as it stands he'd be more valuable to a team that has nobody else in his way than he is to the Sixers, if he needs to prove he can stay healthy why even keep him when you already have a center that projects out to being very similar to Boogie.