"republicans" becomes a fuzzy thing if the republican POTUS wants to expand social security, walk away from trade deals, and move towards a public option (as examples). since he is "republican" the moderate republicans can break ranks, he being "republican" gives them cover, but these are things the Republican Party is firmly against ... so it blows up the party. A cohesive left is the only real game left in town. That the "republicans" outnumber democrats in congress only means somethingif they excercise cohesion at some level. When faced with the black guy they band together and obstruct, can they do the same with a rich, white, bigoted, misogynist a-hole?
alternatively, a Trump POTUS finally leads us to a multiparty system in the US, hard to imagine without a proprtional congress, but who knows.