What gives you the idea that the left will take over? Over half the military including top brass support the right. The citizens on the right are much more heavily armed that the left. The fact that paramilitary groups on the right get preferential treatment from law enforcement and that militias on the right outnumber antifa 100 to 1. The right is easily powerful enough to win.

the real problems will start when their infrastructure starts to crumble like a Miami condo

On the brink? You're knee deep in it. It's an ideological civil war, much like the 'cultural revolution' under Mao, but updated, modernised and televised. And it's not just the not-so-United States, but all over the western world.

Depends on what you mean by "civil war."

If you mean a shooting war, there will be no such thing. I strongly suspect that - very soon - some staged event involving a "white supremacist militia group," probably in either Texas or Florida will be held up as proof positive that the military must now be involved in order to disarm America "for its own good." There will be some armed resistance, but largely, lawful gun owners will not put up fight because as much as they might believe in the principles of the Constitution, they care about the safety of their wives and children so much more. It's a rare person that will sacrifice their families for a principle, especially in the face of overwhelming pressure.

If you mean an ideological civil war, that's been going on for over a decade now, and kicked up a notch when America chose "the wrong President." It was expected, of course, that after voting a black man into office that the next "correct" course of action was to elect a woman, irrespective of the job the black man did as President or of how much so many in the nation loathed the woman in question. (I still maintain that if the Democrats had truly wanted a woman elected in 2016, they should've put up Tulsi Gabbard.) What the political establishment didn't count on was just how PISSED OFF the average voter was at the state of affairs with governance, to the point where they'd be willing to vote in a political outsider with no connections because he wasn't "more of the same." As a result, the political establishment decided to punish all us plebeians, because HOW DARE we disrupt their careful machinations by voting for the candidate of our choice. Now they have to take steps to ensure we are never allowed to do that again, by censoring opposing viewpoints and publicly vilifying anyone - white, black, brown, male, female, straight, gay, or any shade in between - that does not toe the line. Their test case were the COVID emergency powers they granted themselves and they haven't stopped since.

If the US Military isn’t brought into this it may be quite simple.

Close off ALL Access To and From the Greater Metropolitan Areas who are pushing Subjugation on ALL the “Red Areas”.
Shut off Their Electricity, Water, Food, Transportation, Fuel, Money and Turn Back ANYONE Trying to “Escape”.
EVERYTHING They NEED to Survive comes from ALL of those “Red Areas” including Individual Counties.
Stop Supporting … Providing For … those “Blue” … Predominantly Democrat/Leftists’ NEEDS and see how long They Last.

If the US Military IS brought into it, it will be Harder … “Red Areas” will simply have to adopt a Scorched Earth Policy.

Perhaps it would be useful to see a map of the situation …
Remember … even those places shown as “Blue” are only “predominantly Blue …
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The problem across the planet is one of lawlessness. When you allow the law to become an ass, and the cops are political goons there is nothing left set the high bar.
We have arrived at a point where leftist corruption, dogma and diatribe have taken over.
There will always be those who stand up against corruption. History will prove this once again.