Trump might not even be opposed to universal healthcare in general, so this could actually be plausible. Trump would call it an "Obamacare replacement."
If a Trump Presidency has any disastrous blunders, it would be in foreign policy. In that sense, his Presidency could be akin to LBJ's.
I got the idea because Trump did defend Single-Payer in the GOP debate. If he got elected, the Democrats would probably sweep back Congress in 2018, and they probably would be Sanders Democrats, and push for Single-Payer.
um, I hate to say this
but what on earth makes you assume that?