Theoretically they can ban you from ever entering the US again even with a valid foreign passport. In practise this doesn't seem to happen. But I guess you neve

Theoretically they can ban you from ever entering the US again even with a valid foreign passport. In practise this doesn't seem to happen. But I guess you never know when they'll start enforcing that rule. There are also complicated tax implications - basically they treat you as if you died and tax you one time on all of your assets.