I could see McDavid playing center but Hall taking a lot of the faceoffs. I remember Colorado doing that a lot with MacKinnon I believe. We'll get a better idea about how McDavid can win draws in camp though. He's got some strength. He might be good at it right out of the gate.
But no, it would not be insane to even start McDavid on the wing. It has happened to guys like Stamkos and Crosby even. It doesn't have to be for a long period of time, and it would only be for the benefit of the player. If McDavid solidifies himself at center during pre season, against NHL competition, then I'm sure he'll start there. There are a lot of extra responsibilities at center compared to the wing, and as far as I'm concerned those who say he MUST start at center are part of that wave of hockey fans who are putting too much pressure on him because you are assuming he is so special that even at 18 he will be close to his full potential. There's a chance he'll need some sheltering, and that's okay.
But we'll see in pre-season of course.