Haven't seen the movie, but this popped up on X:
Obviously it's (bad) fiction, but I am intrigued by the "Loyalist" states. Of the Low Hanging fruit, there's already an existing
independence movement in Hawaii, and Alaska only barely considers itself part of the US now. Hawaii would be gone, and Alaska would only be loyalist until it was inconvenient.
I'm also skeptical of what, besides brute force, could make Kentucky and West Virginia side with DC and New England over the "FL Alliance" (Except maybe that name). It would show better writing, world building, and some effort to have researched the situation if they had VA split roughly on the I95 corridor, and western VA, WV, and KY side with the Alliance. The same might hold true of the Appalachian Carolinas.
Out west, depending on their political lean they could have had the
NCR 'scuse me the Republic of California lose some of the Mojave to loyalist Nevada, and pick up a couple hundred miles of coastline up through Seattle. Central and Eastern Norcal, WA and OR east of the Rockies would likely be in the "Western Forces"
I find it plausible that Texas will try and go it alone, and Mexico will conquer them.....again.