I imagine that's the case.I think that what is most likely is that Trump would resign if things were looking that bad. Pence would become president and then everything would get swept under the carpet.
The interesting question is at what point do the Russians decide he is no longer an asset? Do they then release what they hold on him?
What's concerning though is the loophole in Presidential succession. 3rd in line is a partisan appointment that does not need to be democratically elected. If the Republicans saw a double impeachment coming they could just replace Ryan with anyone they want - someone the public might really not want.