While I would prefer one money for all, I think the most likely route is dual money. I can never see the state losing control of their shitcoin USD, and with that people will be spending the worse currency and saving the money/commodity that is bitcoin. Kind of like we have now. My opinion would change on this though if they started calling bitcoin money, removed cap gains taxes, and more avenues opened up to spend in bitcoin in the U.S.

It just hasn't happened yet, as much as I would like it to.