The districts are redrawn in 2020. Bernie on the ticket + youth vote = left-leaning governors. A vote for Sanders is a long term investment. Can the Dem candidate in 2020 put together a coalition to go fix these last 10 years is the question.
There are 12 states with gubernatorial elections in 2016 and 2020. Of those only 4 arent already held by democrats. You can forget about Utah and Indiana going D. North Carolina is the only state that you could reasonably expect to get flipped to D if Bernie turns out the vote. On the other hand you could very easily have Missouri go from a D governor to an R same thing with West Virginia.
There are 36 gubernatorial elections in 2018, which is a midterm election. Guess who doesn't show up for midterm elections..................................the youth and minorities. Who needs the youth and minorities to vote in order to win..................................... Democrats.
Depending on the youth vote is a very dangerous thing as the youth have to be motivated to come out and vote while the older voting bloc tuns out regardless. If Bernie gets absolutely nothing accomplished his first 2 years due to republican led gridlock (which is the most likely outcome) the youth vote will be even smaller than it already will be in a midterm election.