Is it possible? Sure, it could happen, but it is highly unlikely.
5000 passing yards and 50 TDs, could be done.
Mahomes could get 5 rushing TDs on goal line scampers to the pylon, but those would effectively be coming at the cost of a passing TD.
The only scenario where I see Mahomes averaging 32 rushing yards a game is a season were the offense is not producing at a rate to meet the 5000yd/50 TD mark and Mahomes is constantly forced to run. (see Titans game).
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