Brilliant! Arizona, California, Nevada, New Mexico and Texas will be taken by Mexico. Fill up the Mid West with Muslims who will form their own Caliphate. The North East will be taken by Canada. The South may remain independent until conquered by one of the other countries occupying the continent where the United States once governed.
I actually expect some morning we will wake up to news reports of exactly that happening. Arrangements will be made & coordinated, radio stations of certain persuasions will announce "It's time", and a plurality of residents will make clear their allegiance has changed and the area has changed hands; dissenters will be, um, dealt with. (Basically what happened in Rwanda.)