All true. Every state is divided between right and left, and most people may not fall into either camp or don't care about politics at all.
Also, secession assumes that change stops when the country breaks up and each half puts itself under the control of right or left. But change is constant.
Fifty years ago, conservatives were complaining about East Coast liberals. We still are, but there's a lot of complaining about the people South Carolina or Utah or Arizona -- states once thought to be securely conservative -- send to Congress.
The conflicts we're dealing with involve trends going on over the whole Western or developed or free world. Every country has its corporate class and its political Establishment and that would be true of a seceded "red state America" too.
Meanwhile, if progressives keep going as they have, sooner or later, even the blue states will get sick of them. Politics are Fantasyland and someday the bubble will pop. Urbanites probably won't vote Republican, but they will back away from the ledge.
Plus, people aren't going to love having to go through check points to get to work or go shopping or visit relatives, or having to build twice the factories and facilities to produce half the output. I think the country will come to its senses somehow before we get a donut-hole or a Swiss cheese America. China overtaking the US may finally wake us up.