Even something like Texas that is doing well economically because of oil. Once that starts running out in a few decades, what's it going to have? Longhorn cattle?
Already, in fact, right now, today, as a result of anti-abortion laws in some states, not only are people ditching plans to attend medical school in those states, a lot of doctors and whatnot are already moving out. There's a brain drain going on, because people don't want to chance going to jail for doing their jobs.
What are people from those states going to do in the future when going to the doctor means having to cross state lines and now they can't because it's a separate country and the medical coverage they no longer have ain't covering crap?
A funny comment I saw on Quara a few months ago regarding the question of the United States being divided into two countries said, "Good, this way the Blue States can keep their money and not have to waste it on Red States" - something along those lines.