It would take something really bad before this would even be possible. If it did—like the confiscation of all private firearms and all privately held gold—Texas would be the first to go—followed by the states closest to her. A new CSA —now the Constitutional States of America would form. With Dallas as the Capital. Other states would leave as well, Alaska would become a Republic with Russian support, Hawaii would become a Kingdom again and Independent. Next would come CW II . and that would be the end of USA as a great power. Let Russia and China have a go at running things for a while.
Actually, I think the breakup of the US is a normal part of its evolution. And the same goes for every other large country presently extant.
The time of giant nation-states is over.
The concept is hardly original to me. Jefferson even wrote about it; I haven’t been able to find the reference for this, though. I’m not an early-American specialist.