Wank fantasies on /pol/ aside, I don't see a whole lot of people interested in insurrection. The militias may go nuts, I wouldn't doubt the possibility, but those militias were thoroughly infiltrated by the FBI decades ago. A Sovereign Citizen can't take a shit without it turning up in an FBI informant report the next day. And alot of them are all talk, to be honest.
It depends on who does the impeaching as well, of course. If the Democrats do it, and lets be honest they're probably the only ones who will, then the chances of more people going nuts is higher. If the Republican Party turns on him, he'll have considerably less support. And by and large, the people who run the national security apparatus hate Trump. Military, intelligence...you look at their leadership, their officer corps, and by and large they know the man's a walking liability. And the performance last week with NATO and on Monday with Putin just reconfirms it.
That's not to say you need an officer corps for a successful coup - but it increases the odds.
Civil unrest would be more my concern. Alex Jones and Sean Hannity and Tucker Carlson whipping the lardass Confederate flag waving contingent into a frenzy, where they decide to go smash in some local minority's windows. Local PDs standing by and letting it happen. Lynchings. Maybe some riots. Amateur hour domestic terrorists, copying recipes from the Anarchist's Cookbook and blowing themselves up in the process. Couple of assassination attempts. 1960s style political violence.