If Mueller released a tape showing Putin hand delivering suitcases of money and gold to Trump personally, Trump would not get impeached. Its all tribal politics now. Sure we are still a democracy, but its democracy closer to what you call democracy in the Phillippines (at least we aren't Brasil!!!!!!.....yet).
As a country we've had our troubles before. The south in the 60s, a couple of red scares not to mention more than a few uber-wealthy men putting a major stamp on US politics (Carnegie, Stanford, Rockefeller etc). However usually the govt. (and to a lesser extent the press) has done the right thing, eventually. I just don't see it right now. The 2 other branches of government are all too happy to give up power to the executive branch these days, whether its on a local level (police) or a national level (president). Sure congress is all we have to stop Obama or have to stop Trump, but what you don't see anyone really standing up to say we have to curb executive power.
I doubt anything catalysmic is going to happen under Trump. The problem is the millions behind him that will support him no matter what. The question is how do you change this? After all how do you convince millions of people who want to be lied too and be blackslapped with empty promises to change? With facts?? The real scary part is if they don't change (luckily history says they eventually will, usually that happens when they need govt to bail out their behinds) someone even worse and who has a brain in his head will get in.