Are you assuming some sort of retaliation on the part of the Republicans?
You would think Republicans would be smarter than that. Impeachment backfired on Clinton because people recognized that the impeachment proceedings were based on a questionable premise. (Yes, perjury is a crime, but it was regarding sex.) However, we aren't getting the same sort of blowback with Trump's impeachment, because Trump is an individual who has actually committed serious crimes.
If the republicans decide to impeach someone, they had better ensure that the person did something significant to warrant it. Yet Obama ran a relatively clean administration, and the Democrats do seem to be better at picking candidates with decent morality.