Several things that would happen. The largest one being that the New North America would lose all of its trade that had come overseas. While the rest of the world would lose debilitating amounts of financial capital, humanitarian aid and trade with the one of he largest economies of the world.
Mexico has lost quite a bit of its territory and there is now longer a safety valve of encouraging their poor over to America. Plus most of the refugees on the Mexico/American/Texas border aren’t going to want to settle in a country that is structurally damaged and facing several insurgencies and is quite a bit authoritarian. Mexico might actually attract refugees in White Southerners moving their to escape the retaliatory executions carried out by the US army.
considering the ISOTed US is a somewhat a socialist country, they might to try and extend ties to some of the socialist holdouts in our world.
Their might be calls from the world, especially Canadian immigrants in other countries, for the United States to let Canada go. But since the world is probably in a bit of a pickle, it’s not going to be pressed too hard.
The UN would definitely have words to say about the US policy of retaliatory executions and the treatment of the Mormons. But again, the world is in a pickle and the UN has other things to worry about.
like an ascendant Russia, China, Iran’ and their Allie’s being able to more easily push their agendas with America out of the picture. Along with several insurgent groups getting increased recruitment because they would most definitely see this as a sign from Allah. To many young impressionable Muslim men…it would seem very reasonable.
A lot of the nations in the Caribbean and Latin America would be facing serious financial crunches as they would be losing huge amounts of remittances. Which would most likely send those countries into economic recessions, if not outright depressions. Expect to see more Latin Americans moving to Europe/Australia or the more economically successful Latin American countries such as Brazil, Argentina, Mexico and Costa Rica. To name a few
Several US backed repressive governments would be facing extreme internal strife and possibly outright rebellions.
So in a nutshell, the world is going to have it pretty rough
Also are the islands in the pacific under US occupation coming as well? I just want to make