I would like to think that, despite the high present level of polarization, civil war in the USA is exceedingly unlikely. Your institutions and history of civil stability are too strong.
And also, Americans are too fat, lazy, and addicted to our lives of ease. There is also not a serious disenchantment with the current
form of government, just the people who happen to be in office in that government at any given moment.
A real civil war would require commitment to years of pain and suffering as well as a genuine disenchantment with the current form of government.
What we have now is a fringe of lunatics which is increasing greatly in bellicosity and moderately in size, fed in their extreme philosophies by Internet echo chambers that keep them convinced "The other side is is coming to get you, and they will succeed unless
you take action
now!"
So the US is going to suffer more lone wolf attacks, but it's never going to scale up to an actual civil war.
However...I suspect the intensity will actually diminish substantially when the Boomer Generation dies. We Boomers were the last generation that was born and raised in social and ethnic apartheid, and we make up the bulk of hard-core extremists. Unfortunately, we Boomers still control media, industry, and politics.
We Boomers certainly have a reflection of our attitudes in the X Generation and Millennials, but it wasn't inculcated into them from birth with absolute social thoroughness as it was with Boomers and earlier generations. It's likely to die out in their generations once Boomers are no longer around to keep the flames fanned.