Danny isn't going to let Jaylen just walk, unless a better FA opportunity or trade makes it necessary.
Even if Jaylen isn't going to be a 2 way all star, he still looks like he's going to be a very good 2 way player. He has a lot of value, which, worst case, Ainge will leverage in trade. Personally, I think the Celts still believe he has all star potential. He's only 22 years old. Jimmy Butler averaged 3 pts a game as a 22 year old rookie, so it's still early to pencil in what kind of player Jaylen will be for the next decade.