The issue won't be talent this year, but circumstance.
Right now Bass and Green are ahead of him on the PF depth chart. While there is some talk of him being able to play some center, I'm not so sure he can play an undersized 5 next to undersized 4s like Bass and Green.
And if that's the case, it pretty much leaves him playing next to KG or Wilcox, which means he's really playing PF and competing with Green and Bass for minutes.
Now could he potentially beat Green and Bass out for minutes? Yes. And I hope at least with Bass he eventually does. But after Bass signed a 3 year 20 million dollar extension, I don't think the Celtics will be too keen to exile him to the bench right away and essentially destroy his trade value.
So I think if Sullinger does beat out Bass, it's going to have to be a big time beat down that Doc can't ignore, not that he just marginally outplays him.
The silver lining is that with Bradley out, I wouldn't be shocked to see PP get 5-10 mpg at the 2 guard spot, freeing up Jeff Green to play almost exclusively at the 3 spot. That should in turn free up substantial 4 minutes for Sullinger.
If he makes the best of it in the first month or two of the season, maybe Danny will look to move Bass at the deadline.