There are 3 possibilities:
1. The optimistic scenario
Mainstream Democrats will realize that Clinton is a flawed candidate, and Bernie Sanders will win with significant super delegate support.
2. The next best scenario
Bernie Sanders concedes at the convention with a two part speech. First he endorses Clinton, and then talks about how we are going to hold a Clinton administration accountable. The strategy is exciting enough for us to rally around, and we go on to elect Hillary while continuing to build a truly Progressive movement. Clinton finds that the only way she can get things done as President is to earn the support of a very active Progressive movement that focuses on specific policy issues.
We protest and block weapon sales, and we get a $15 minimum wage in most states. We make significant progress with criminal “justice” system reforms, and take some real steps towards treating drug use as a medical issue instead of as a criminal problem. After a few more massively destructive weather events we finally make some extensive investments to deal with climate change. We fight for a single payer option as part of the Affordable Care Act, either requiring Medicaid expansion or by establishing many more government funded community based clinics. And we support a Supreme Court nominee that will overturn Citizens United.
And we work for peace instead of war and somehow manage to hold back the neoliberal war machine from making things worse instead of better.
3. OR, the What if feels like reading DailyKos scenario
Clinton wins the Democratic nomination and continues to alienate Bernie Sanders’ supporters. Donald Trump is our next president.