We always wanted a can opener as our big signing, didn't we? Somebody who would engage defenders 1v1 during a tough game. While I think that missing Dybala is not a good idea considering he is being offered to us on a silver plate, he is probably not the man for the described task.
Players who could engage in one on one vs defenders are usually wingers, and I don't think we will switch to wing based formation. Yes, there are AMs that could do that like Firmino or Isco, but they are rare. Formations that utilizes AMs in itself are rare. But who knows, anything can happen, maybe we will switch formations or buy that Fantasista that everyone dreams of.
IMO, signing Dybala is for the purpose of replacing Tevez, which is vital. I know that Tevez is still here next season (hopefully), but isn't it better to let the replacement gel with the team so that when Tevez really leaves, the replacement will be ready?