Since the GOP's attempt to repeal and replace Obamacare with their god awful bill failed, I think that the next Demcratic wave won't push for single payer but will instead try to transition the us healthcare system into a multi payer system like Germany or the Netherlands. Now if the GOP healthcare plan had actually passed, then single payer would almost certainly be on the Democratic Party platform going into the 2020's.
I think it will. single-payer is something that I expect Bernie to grandstand and work behind the scenes to force the progressive wing into supporting it. He might make 2020ers sign onto it for his support, for example.
