Not sure if Ehlers stays or goes. Both paths have their risks. If he stays he's having to compete against younger prospects who will be given every chance to succeed and have to fight for his icetime even as he's slowing down a bit, potentially.
If he goes, he's spent most if not all of his prime here and will have to start all over again with his new team, establishing himself in a new hierarchy and having to win over a new coach and management team, fanbase, etc.
He's a unique player, and like other outliers we've seen with the Jets, tends to produce some polarizing responses. Easy to remember the force of nature and superb overall defender Buff was, but the hate he got from some of those in our seating group when I had a mini-STH package was pretty consistent. Riverboat gambler, can't play D, blah blah blah. He got his due eventually but there were plenty who didn't get his game, which is fine, that's fandom.
KFC is an easy player to understand, and like. Excellent possession player who is brilliant on the cycle, a remarkably consistent scorer who can be absolutely ruthless over stretches, and a terrific passer also with great vision and patience. Agree with
@Gm0ney that Ehlers can look like he's playing a riskier game even when he's driving play and helping to win matchups.
But the Jets are better with him than without. He's a gamebreaker who can create space and chances for his linemates and he plays with passion and rarely lets up. He can be expensive in he can lose the thread of a game such that his timing is off and he's making passes and plays that work for him and no one else. But he can also take over a game and win it pretty much by himself and such players are rare -- we've seen JMo do it, and Scheifele too, but you don't let such players go easily, especially when they're productive 5v5 players who can also gain zones and open up lanes so reliably. And he has an absolute blinder of a shot.
And finally, and maybe importantly given the recent Bettman trip, he's a player who can lift a crowd and electrify a building when he winds it up or drives a puck and that is worth something for a team that is finding it harder to fill the building even as a top team in the league.
If I were Ehlers I'd look at my options carefully. And if I were the Jets I'd take the time to think about what I might lose, and how hard it would be to replace.
I'd miss him.