Of that 70m, how many would vote for Trump as an independent if up against a Republican? My point is, not all those who voted for Trump are Trumpites but plain old Republicans.
The thing is though, that that doesn't really make it any better and it shows that there is a real issue with US politics that's not easy to solve. After this election and Trump getting 70m votes, I honestly don't know how well a monkey named "Mr. Pebbles" from some zoo in Florida would do as the Republican candidate. I'm pretty sure (but not 100 percent certain), that he would not win the presidential election, but at the same time, I'd also say that he'd still get tens of millions of votes just because of the "(R)" behind his name. The thing with Trump is that he managed to appeal to a certain part of the population who decided to join his cult, while apparantly also getting loads of votes from people who don't care about the candidate, but just which party he belongs to.
The whole two-party system in the US makes it even worse, because things are getting partisan. Us against them with them being the other party. So the whole country is divided and it's basically going back and forth between the two. One term that party is in charge, the next one it's the other one. There's no real reason for compromise, because you can focus on getting the win in the next election and get it at whatever cost is necessary. It also leads to people voting for some guy who might not be their cup of tea, but they have to because he's from the party they support and they would never vote for the other guy. That might have been okay a hundred years ago, but in today's world it is messed up in my view.
And the worst thing about that is, that I don't see a way how this is going to change. The alternative would have to be that there are also other options, where someone like Trump maybe gets a couple of million votes from the complete headbangers, but people who might be conservative can vote for someone else. In my view, that's not going to happen in the forseeable future, because the established parties already have so much power and even worse, money plays that big a part in US-politics...