Have no fear, if it turns out there is actionable evidence against Trump or his team, and it goes south quickly, I have no doubt that the Republicans would drop Trump in a heartbeat.
I don't think any of them actually like Trump, but, when in Rome etc.
Pence is someone Republicans could more easily deal with, minus the endless baggage of our current twitter-finger President.
It's entirely possible that the FBI investigations of Trump and his team last for another year or two - whatever you think about that, it's just a huge distraction.
When (or if) push comes to shove, Republicans would drop Trump like a prom dress after midnight.