I think many Republicans envision installing the party much in the same manner as the PRI once was in Mexico - something that creates the appearance of democracy, but is essentially an oligarchy with new leaders at the top every eight years.
But let's assume the best for a moment.
Impeachment only becomes a possibility if the Republicans see Trump as far more of a liability than an asset. He's off the rails, but (from their standpoint) he's getting shit done: he's reshaping the court; he's cut corporate taxes; he is punishing Hispanic immigrants; rolled back the EPA regulations; gotten out of the Iran deal; put the Cuba deal on hold; gotten firmly behind a Middle East peace deal that sets Israel up as the clear winner and the Palestinians up as the clear loser; and he continues to do nothing to interfere with gun ownership. They are on the cusp of rolling back most of the Warren Court decisions. They may have liked George W. Bush a whole lot more as a person, but he failed to even scratch the surface of the to-do list. But then come the mid-terms, and they know they are likely to lose the House, and they know that Trump will play brinkmanship with shutdowns, and they know Republicans will get the blame for that.
If they lose the House, he next thought turns to 2020. Two years is an eternity in American politics, and history teaches that Pence could conceivably take office; pardon the Trumpsters, and still have a fighting chance of winning reelection. They desperately want to hold the White House and the Senate to replace RBG and Breyer. So one scenario is that the general sense that he is off the rails (brought about by Fear as well as the NYT leak) carries forward past November. Let's further assume things don't get better on the Muller front, and possibly he starts a purge after the midterms. At that point, the Lame Duck GOP led House may surprise everyone and make a quick move for impeachment. They can dream up one of a hundred high crimes or misdemeanors. The Dems, who will smell the rat, will still willingly go along - and not too many Republicans will have to sign on for this to work. Then on to the Senate. At this point, Mitch will present the deal to Don Sr. - resign and Pence will pardon you & your kids fully and unconditionally, or we will try you in the Senate; throw your ass out; and feed you to the Grand Jury. The Kochs and the Ricketts will sign off on that, and Mike Pence will be hailed as the savior of American democracy - which he will continue to erode, but in a more civilized manner and with less use of Twitter.
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