If Trump actually acts like Trump while in office, I suspect the Republicans might go ahead and allow an impeachment to proceed the first time he acts too Trumpy. They'll wine and make a fuss of course, but secretly free up votes to support it so they can go business as usual under Pence.

But what is more likely (well a Clinton presidency is still most likely but beyond that) is that Trump will be out of his league and the Republicans will leash him.