Though it's not likely gonna ever happen, but if this would really happen then I would sell all of my bitcoin, because I don't think it would stay in $1M for a long time. I'm sure when this happen people will also sell their bitcoin and that makes bitcoin price drop hard.
I think that I would do the same, I think that everyone would do this because it would most likely make you a millionaire, I think that this is also never gonna happen but thinking about is already awesome.