If there was a second US civil war, what would the two sides be?

It would be the angry folks, who believe their entire way of life is being stolen, or becoming extinct. Many of these do Correlate to certain political movements.
And their enemy, would be anyone who is not exactly like them. So every minority weather ethnic, cultural, or sexual.
Much of this was also correlate with the world versus urban. It is very hard not to give both of these groups apolitical label

The lefties Vs. The righties. The righties would win…we have more guns.

Red and blue idiots.

Magats vs Patriots. With moderates, centrists and independents trying to "compromise". Then you will have opportunistic warlords rising: Nazis, kkk, various Christians cults, etc...
The first civil war was easy as far as civil wars go due to the clean geographic split. A second civil war would be so mixed up even family members would be killing each other in their own house.

I imagine the scenario would be an increasing level of lawlessness and social unrest due to crushing economic realities and the weakening of the ties of social cohesion

A heavy handed response triggering the rise of the disaffected

However I don't foresee any cohesive leadership emerging

Nor people uniting across identity divisions

And then there's the generalised American hatred of 'socialism' would work against a French or Russian style of uprising

So I actually think that America is safe from civil war for now, but that doesn't mean everything is going to be pretty