@MontereyJack,
You don't know how the election is going to turn out.
Even if you turn out to be right about the election results, you are wrong about that meaning no investigation is possible. All Mr. Trump would need to do is appoint a bunch of independent prosecutors to endlessly hound the Biden Administration.
Then when the Republicans retake the legislature in the midterms, they can base their impeachment efforts on whatever the independent prosecutors have turned up.