I’d personally like to see two parties: a Far-left and a Far-Right party so the two parties we have now can gravitate back toward the center where they belong.
That's how things gravitated in the latter years of the Weimar Republic, with the political energy tending either to the Far Right (Nationalists and Nazis) or the Far Left (Communists). The Parties of the Center Right (Center) and Center Left (Social Democrats) could not deal with the coarsening of political rhetoric arising from economic distress, and the extremists turned into brawling tribes.
America does not have a strong Socialist party.