I think the Bills want to roll with shakir. I don't believe that either McKenzie or Crowder are under contract next year so Shakir will be the uncontested starter.
Chubb is a different case in that he could spell both Von and Groot.
Ernie Acorsi who built the world champion giants said you can never have enough pass rushing DEs.
So you could have Chubb opposite of Von or opposite of Groot and rest Von. You could even sprinkle Boogie in there keeping all 4 fresh for the end of the game and even the end of the season