"Besides, Russia now has the entire Republican Party under it's thumb."
I agree with that part. At the moment, anyway. But that can and probably will change after the midterms when it's time to pay the piper for their cowardice. They'll no longer be useful when that happens.
In fact, Trump himself won't be of much use to Russia either. He's already under attack by incoming from all directions. His presidency, such as it is, hasn't even seen the worst of it yet when Democrats get the power of subpoena.
How useful do you think he'll be to Russia once he's been exposed and no longer has free rein to help them with their expansion? In fact, how useful will he be if he doedn't even finish out his term?
That's the whole plan isn't it. Force him to resign and take his no-account brood with him. Then we'll see if Pence has learned any lesson about what happens to presidents who engage in subversion.