I think he'll return to form next season if they get a new QB coach and a real OC. Remember he had his best year under Reich and Defilippo and hasn't been the same since they leftA Wentz trade doesn't impact the cap, he's set to be a $34m cap hit whether he's an Eagle or traded elsewhere.
If he isn't the starting QB next year then both options are ugly, whether he's a $34m dead cap hit in another uniform, or a $34m backup QB here. The benefit to a trade is acquiring an asset and saving money moving forward. If he's traded before the 3rd day of the new league year (March 19th 2021) there wouldn't be any money on the books for him in 2022 and beyond.
I personally don't think it's gonna happen, but if Jalen impresses them down the stretch it becomes more and more realistic.
He's regressed because he's being enabled and not coached. Couple that with the depleted rosters post superbowl and stale playcalling