Ugh. Ok, you think theyre going to watch an impeachment and act like a bunch of republicans and not have a replacement for Biden and let the republicans put their guy in?
This conversation is over
Duh! Read the 25th Amendment. The 'Rats wouldn't have a choice.
If we had enough votes to oust Obama (two thirds), we would also have enough votes to deny Biden's choice for a VP (a majority), and likely also enough votes to oust Biden himself (two thirds again). Whereupon Boehner (or whoever may have succeeded him as Speaker by that time) is next on the list.
Of course, it's all fantasy. It would take quite a November to have 67 senators. But if it were to come to pass, the Democrats would have no opportunity to replace Biden on their own.