There is no way Bernie or Hillary will run again.
I happen to feel Amy Klobuchar is underrated and would make a good president. But assuming Kamala Harris (meh) would run, it would get messy racially, like why are we replacing a black woman with a white woman?
Buttigeig is brilliant. Americans don't like presidents that are too brilliant so I don't see his lane.
However, Biden is running, so this is all academic.