If he'd agree to the Hawes deal and take 2 years and 13 million, I'd be all for it.
I think we have to be cautious about giving him 4 years. He plays the game he plays quite well (hitting open jumpers and dunks), but he doesn't create his own offense. I think there's a shot JJJ and/or Sullinger could pass him on the depth chart this year. And since all three are pretty much exclusively power forwards, there's not really any good way to get them all minutes.
When you combine that with the fact that (assuming he returns) Green will get significant minutes at the 4 (there's no way to get him enough at the 3 exclusively), and I think there's a decent chance Bass could be out of the rotation by next year or even earlier.
The problem then becomes how to trade him. I think he has OK value on a 4 year deal 25 million if he keeps playing, but if he gets bumped from the rotation, his value will plummet, and we'll be stuck with an unmovable salary.