It’s a long way to November. Hillary and Trump are the most disliked - according to the polls (the polls have been repeatedly wrong) - and both are in the lead as their parties presidential candidate.
While some people believe ol’ Hillary is the best choice, there are others who believe she’s the devil/liar/future felon/poor choice. Bernie fans seem to be pissed at the Democrat Party for not treating Bernie fairly. That’s not the same as claiming Bernie and Hillary are the different sides of the same coin so voting for one is the same as voting for the other. They’re pissed at the party.
I think this will be judged in hindsight. If Ryan can hold a traditional-conservative, establishment GOP majority in the legislative branch and the GOP can kick Hillary out in 2020, then he will be seen to have done the right thing. He’ll be principle and independent.
If the legislature loses and/or Hillary gets re-elected in 2020, then he will be seen as a traitor who sabotaged the party and made it too weak to win. Unless there’s another victim who is even easier to blame, like perhaps Trump himself.
Either way, he won’t be judged on what he actually did… the latest election has made it clear that truth has no place in politics.
These will be the national-level issues, at least. He might remain popular with his local voters regardless.