I've waited a long time....I'm and old man and don't have much more time, if I'm going to participate in the defense of the Constitution and the Republic..
The closest example of such a thing taking place in recent times would be the Finnish Civil War of 1918, in which the Finns exterminated the Communist revolutionary threat in their own midst. The cost was the death of around 3% of the population of the country, that in a 4-month long bloodletting that would almost certainly be much more protracted in this time and place, and of course far more brutal if the other side thinks they have a chance of winning through NVA or Mau-Mau style intimidation...particularly if foreign nationals from south of the border choose to participate.
I do not look forward to the idea of such casualties here, but it may well come to that. And remenber, if you are not helping to train junior officers and subordinates, both by lesson and example, you're not doing everything you could be. If you are, then you can be much more satisfied that the situation will be in good hands long after you are gone.
In such places, I would not want to be living as part of a minority ethnic group, when TSHTF. It will be very brutal, with Stalinist martial law being imposed by future Mayor MECHas as the only alternative to Mad Max warlordism.
Naturally, this presupposes our national economy will by and large collapse. Anywhere you picked to live had better be near its own supplies of food and water, and very far from large urban areas. At least 300 miles (a tank of gas by maraudering gangs).