Jeeze I never thought about that. Impeaching Biden. Yeah...that could be a thing although both Trump and Clinton have proven that impeachment alone means nothing. I honestly would hope Republicans don't even bother. It is infinitely more damning for them to demand investigations into this and put Pelosi and the rest of the cabal on the spot.
On a whole other note, I'm sure you will all disagree, but I think you consider this thought, that is, if Trump is either legally successful in his cases and/or the 4 recounts (yes folks that haven't been paying attention, we're up to 4) we're up for favor him and he is then declared the winner, he ought to resign. I'm quite serious about this. It is certainly clear the Left will not relent their contempt for Trump and his supporters whether Biden is declared the winner or not, and and there is no reason to believe most Republicans/conservatives will accept Biden as President.
Trump will have to deal with Nancy Pelosi for at least another 2 years. Clearly that will mean continued investigations against him, his family, and his supporters along with virtually nothing getting done in Congress for just those 2 years. The media (which I include social media) will continue spurning Trump as they've been doing for years. Antifa/BLM will raise their ugly heads again with renewed ferocity. In short, it will just be another miserable slog for at least 2 more years if not 4. Why not bow out after if he can secure a victory for himself and Pence? It would still be one last FU to the Left, and he could manage to heal some of the rifts in the country if he did so.