Civil War 2 is interesting to theorize about. One thing to keep in mind is geography and demographics and how that would influence things. The problem for the left is that all of their support and institutions are based in a few big cities that are spread out from each other, separated by large swaths of land that would be controlled by the right. In an actual wartime scenario I would think that would be a fragile setup for them (the left). The right, with a bunch of armed, middle class, rural, and suburban families with big military support will know EXACTLY what areas to target in a civil war. NYC, DC, Philly, Boston, SF, Seattle, LA, Chicago, Detroit, etc. The left might be able to take over the northeast corridor and the west coast (just the parts right on the coast, not the California central valley or Eastern Oregon and Washington). Those are the only "extended geographical areas" I could see them holding at the beginning of a conflict. If you cut off food resources to those areas and focus your tactical efforts there, then what the fuck is the left going to do? Bomb Wichita, Kansas? Take over Grand Junction, Colorado? Poison the water in Mobile, Alabama? What effect is that going to have on the larger right-wing war efforts? The right is much more spread out and doesn't have a clear target to hit that would be very devastating (overall) in a war. The left has 10-20 big cities that hold all their major institutions and populous and resource-wise are very fragile.
If we had an open nationwide civil war, I think the geography and way the population is distributed in our country massively benefits the right strategically. How is the left going to invade the heartland and entire interior USA without complete 100% military support and a pool of people who generally are not armed? Meanwhile, I could see groups of a couple thousand right-wing people from rural and outlaying suburban areas taking over transportation infrastructure in cities and causing massive problems for the left. They could cut off food and energy supply and basically force the urban cores to turn on each other, make strategic blunders, or surrender. They wouldn't even need much deadly force to win. The left would have to invade the interior to win where the right would just have to hold their lands and create strategic problems for the left. If they wanted to do more than that, then it could get very ugly for the left very quickly.
The flip side is if we had a worsening of the "cold civil war" or "shadow civil war" gradually over the next 50-60 years and the left was able to increase it's institutional power to the point where it had the military, FBI, and most police forces 100% under it's control. That is the scary scenario, but I think Trump will end up repealing some of their progress in that side of things, so in the mean time that isn't a growing threat (hopefully). It WAS an increasing threat under Obama though and if there was a scenario in the future where another Obama-like leader took power for 8 years and was followed up by another statist/leftist (like what would be the case if Hillary was elected), we could be in serious trouble.