Bruce Arians... LOL
That decision will be made way above your head, coach. You have a Super Bowl ring because of Brady.
That said, I think Brady really is done with playing. He said something like teammates need him all-in and he can't do that anymore. If Brady isn't 100% locked in, full-on TB12 style with the smoothies, massages, and whatever else then he will fall apart as a 45 year old QB.