Is a second civil war coming?
I think it's possible. There are four things that trigger a civil war in my mind:
1. Dems losing the 2018 mid-terms and starting violence
2. Dems losing the 2020 presidential election and starting violence
3. Dems impeaching Trump, leading to the right starting a violent revolt
4. The US government trying to ban and confiscate guns, leading to a wide-spread revolt of all gun owners.
I feel like the first three are the more likely scenarios based on current events. The last one is just a theoretical future situation.