You do realize that if Bernie Sanders became President, the likes of Manchin, Sinema, Feinstein would still be there, right?
Bernie Sanders, a progressive defender of the filibuster on record several times, would have the same issues of overcoming senate gridlock. He would also have difficulties getting his caucus in line, assuming that Manchin doesn't go "screw you" and changes his party affiliation (i.e. Independent or Republican) in response to Bernie becoming Prez.
This kind of problem isn't contingent on who's President. Unless of course you think Bernie Sanders is somehow the guy who can on taking the nomination immediately exert hive mind control on the US Senate in a way Joe Biden can't.
This kind of grudge-bearing and settling of scores and so on, isn't helpful, intelligent, or informative. It's not concerned with how politics work.