It seems like such a logical answer to the problem, but who would initiate it?
Probably isn't even that logical. As
@wesheltonj notes, I don't believe that there is nearly as clean a geographic separation as the author speculates. There are two different ways to look at popular vote by county in the county. The first, which we see most often is based upon who won the county. This map creates the impression that their is a clear red and blue America with sharp regional differences.
These are same vote totals expressed in density of the population.
Sorry, the second defied my efforts to enlarge, but I think it is obvious that red thickly incrusts an expanding blue in the major population centers. As the author of this map noted, land doesn't vote, people do.
I do tend to agree with the author, that the "progressive" movement has been on the ascendancy for two generations.
This sort of population and geography calculus makes me particularly uncomfortable when both far right and left talk about taking up arms. It won't be against someone hundreds of miles away - it literally will be against ones' neighbors. I have said this before, the closest historical parallel would be Spain in the 30's. Some of the firebrands on both sides need to actually study that charming historical interlude.
Finally, whichever side "won" such a confrontation would have to institute a totalitarian form of government. Such a war would be based upon intolerance for the opponents' ideas - doctrine if you will. God and Capitalism vs Socialism and Secularism? "Winning", inevitably, would entail eradicating one set of those ideas. That is by definition the very essence of totalitarianism.