Well, it does sort of mean that the civil war was for nothing if they leave. And it means, just as it did in civil war times, that other states could leave.
What they could do it split Texas up into for separate states as I believe Texas was given the right to do when it first became a state. It would require some people to move around, but we could get all the crazy fucko's to go to one neoTexas while the sane people go to another, and those in between go to the other ones.
And it also is an issue of not wanting the guilty conscious of watching the fucks 'going galt' and then realizing that they can't survive on their own. And the subsequent watching them beg to undo what they did as they slowly starve and drain more federal money away than is needed. And them leaving would fuck our economy up even worse.