He might actually be worse than Mac next year, but even if he isn't, he isn't going to make that garbage offense any good (even with a different play caller). And even if the Patriots offense wasn't garbage, why would he want to deal with Bill again? Bill is a very large reason why he left.
I'd say in order the top 5 most likely things for Brady for next year are:
1. Stay with Bucs
3. Sign with Vegas
4. Sign with Niners
5. Sign with Dolphins
And I put the top 2 choices at around 45% each (or 90% combined).