When a nation tears itself apart in war, it’s a civil war.
You can debate whether it’s also an insurrection, a rebellion, a restoration, a revolution or a counter revolution.
But it’s a civil war.
Calling it CW2 infers a connection to the first civil war. The revolutionary war was also a nation tearing itself apart so by your definition it was also a civil war. If one had the desire to make a connection between a past conflict with a theoretical future conflict I think it would be wise to connect it with the revolutionary war rather than the civil war.
I don’t see armed conflict as part of America’s final reckoning before we fall as the World’s Superpower and re-organize. Rather, I see lengthy legal battles as a couple of southern states make moves to establish their own independence. Skirmishes may come about when they grant their people and businesses the “State” right to quit paying Federal taxes. The “State” will have to agree to defend it’s citizens from Federal enforcement and that’s where some skirmishes will break out.
The loss of the two states from the current political turmoil will upset the balance of voting power in the electorate and will cause further denegration of a civil society. As others consider sessesion, violence between citizens may break out. But the legal battles will divide and eventually become the unduing of our nation, not the killing in an all out civil war.
...And those are my thoughts on the worst case scenario.