Norm Ornstein saw Trump coming long before I did. There is an interesting interview with him here.
He and Tom Mann wrote a book a while back called It's Even Worse Than It Looks, essentially saying that Congress is in horrible shape because the Republican Party has gone nuts. The interview essentially boils down to this: Republicans are horrible, Trump is horrible, so Republicans will nominate Trump. Obviously, there is more to the story than that, but let's call it the executive summary. And that is why Ornstein's method of prediction will leave many unsatisfied.
Essentially, if you are a Republican who doesn't support Trump-- and there are plenty of those!-- Ornstein is telling you to accept that your party sucks. If you are a Democrat, Ornstein's argument will hit your sweet spot.
So here's the perverse implication. If you are a Republican, you should give Ornstein (and his book with Mann), a close, serious reading. If you are a Democrat, you should be very skeptical.
Why? Because you should be leery of any argument that gives you ideological or partisan comfort, and you should try to embrace any argument that causes discomfort. That is how you combat your own internal biases.
Is that hard? Absolutely. Do it anyway. Eat your damned vegetables.