$20m this year, $13.25m the next. Unless Brady truly doesn't care about money in any way, it's hard to fathom him signing that deal. (Personally, I think Brady cares about money less than some have reported, but I also think money provides him a convenient excuse to leave for other reasons which I'm increasingly becoming convinced outweigh his interest in staying.)
A "bridge QB" probably depends though. Assume Stidham is the starter and maybe Keenum will come for that much (though really he got paid $7.5m last year so unlikely). If Newton gets cut or traded, he might be $20-22m as a starter type (consider that at $16m, Andy Dalton was the cheapest incumbent veteran starter type in football last season). Same for all the other guys like Tannehill or Bridgewater, low $20s is your starting point. It all depends on how sturdy you want that bridge to be.
Unless the Patriots decide to just roll the dice with Stidham and a middling veteran backup a la Keenum in which case the cost is around $20m, it's hard to envision the Patriots paying the QB position less than $30m next year between a veteran starter (thinking Tannehill, Bridgewater, Newton, Rivers level) and Brady's dead money or otherwise if the money goes to Brady himself.