We’d invade you.
Since we’re talking the medium-term future, I don’t see Mexico stepping in and controlling anything beyond the Southwest border region. They certainly wouldn’t have an undue influence beyond parts of Texas if Texas inherited even a modicum of the former military power of the US.
The only wacko scenario I could foresee is if some mountain West states banded together to secede, some deep south states seceded too out of sympathy, and Texas said hey why not and joined in. I don’t think the three separatists would join each other, though. I don’t think the mountain revolt would get more than Wyoming, Idaho, the Dakotas, and possibly Nebraska and parts of Kansas and Colorado. The majority of the population of Colorado is either liberal or military (and thus more likely to stick to the US.) Florida would not vote to secede: they’re crazy, but not that type of crazy.
I think the rest of the country, with the possible exception of Hawaii and Puerto Rico, would remain as one country despite being bifurcated. The rest of the states would still have a larger population than the breakaway states. However, joining with Canada would not be a bad idea at that point, if only to keep the capital far away from people who are angry enough with you to break away.
Presuming that there would be a window of free movement, which of those would you prefer to live in?
Who’s we?
Cephalopods?
Has to be. The total population of Idaho, Nevada and Arizona couldn’t handle South Central LA, much less the ranchers and farmers in the San Joaquin Valley. 
Calamari doesn’t stand a chance.
Colorado would be f’ed. We’re a West Coast state plunked down amidst a bunch of states we have nothing in common with.
On the other hand, we’d dominate any contiguous region we were thrown in with. We’d be like the Roman Empire and I’d live in Rome!
There is a power base there. Call the new nation “Four Corners” and Robert is your parent’s sibling. The parts on the left are on the right, and verse visa.
The non pacific states. You guys have lots of stuff to grab.
Ah, the promised land. Except that SoCal has to go. No Baja either. Don’t fit in with the rest.
wows someone played too much shadowrun back in the day…
No such thing as too much Shadowrun.
Somebody fetch me a sack of D6es.
That’s why we have buffer states. It’s a long way from St. Louis to LA, and no place to hide.
Ecotopia is a nice idea, but I’d rather have a new country that can produce some produce. Garreau’s vision leaves Ecotopia with no way to feed itself except to deal with Mexamerica. My way gets the best of both worlds.
Here’s the plan:
*California, Oregon, Washington and Nevada and Alaska are one country named USOP - United States of Odd People. Politically aligned with Canada.
*Next , draw an east-west line along the southern border of Utah, Colorado, Kansas, Missouri, Kentucky and Virginia
*States north of that line become USTDC - United State of Too Damn Cold Winters. Politically aligned with European Union.
*States south of that line become the USST - United States of Sweet Tea. Hawaii goes here due to it’s nicer weather and love of Spam. Politically aligned with England. The USST won’t like the whole monarchy thing, but does admire secessionist tendencies.
Actually, I DIDN’T remember Igor Panarin until you reminded me.
But man, what an ignoramus! People often chide Americans for knowing so little about the outside world, but Panarin became a celebrity and a hero in Russia for spewing out nonsensical theories with NO grounding in reality!
No matter what noises various segments of the US population may make, we’re one nation, and nobody is seceding or getting taken over by any other country.
I’d like to think Panarin is a clever fraud, but I think he’s just a delusional moron in a country eager to believe what he’s saying.
Oi, leave me out of this!
Restore the Hawaiian monarchy!
Only if the Hawaiians agree to replace poi with BBQ pulled pork.
Panarin had no more nor less credibility or empirical basis than any other of these hare-brained paint-screen maps that proliferated as soon as it was possible to put them online:
I dunno, that is some good shit.
But hell, it is Hawaii, they have both.