You'd be surprised that the value of IT isn't what you think it would be. He happens to be a perfect fit for the needs of the Celtics, we need a scorer badly. Honestly, he's more an undersized shooting guard than point guard, (that's why Horford is getting more and more touches lately, we need a facilitator) plus as the NBA knows, he's a major defensive liability. (he now come's out of the game in close games in the 4th quarter)
IT needs to get his arms around the idea that he has star 6th man potential... that's where his value is, then every team in the NBA would love to have him on the roster. In a future perfect world for the C's, Fultz or Ball play the point, with IT coming off the bench.
If he asks for superstar money, as a starter, on par with Harden, Westbrook, Curry etc. it's a no go for me.