Actually, I think as leader of the Party - President - she can influence the outcome of the local elections. She can put forward a platform that will motivate the electorate to vote for the Dems. If the people that came out to support Bernie feel they have a chance at having their voices heard they just might make a difference.
The Supreme Court appointments are important, and again, as long as she can get progressive Justices in the Court that might help swing the balance.