Time is not on their side, and I suspect History is not on their side either.
Until people start actually voting for (a) third party, I am afraid that rather than being a last squeeze, we will be getting candidates like this more often, not less.
It is entirely possible to support someone's form of leadership without entirely supporting all of the person's ideas.
That's why I specifically said Trump's vile brand of leadership. It's OK to agree or disagree with his ideas, but leadership is far more than having good or bad ideas. Leadership is ultimately about people and having a selfless, coherent vision for the people you represent.