Next time, it really will be different.
Hillary entered the 2008 campaign as a decided, but not overwhelming, favorite. She lost to Obama, not because of any meaningful ideological differences, but because the public preferred a fresh, articulate figure without her baggage, most notably her vote on the Iraq War. In 2016, on the other hand, the only meaningful opposition came from the left, and was ideological. This time, she won.
There will be no clear frontrunner going into 2020. The Democratic base has moved to the left. There will almost certainly be multiple minority and female candidates, and they will effectively be running in separate minority and female lanes. As a result, the primaries will look a bit like the GOP in 2016.
Who will win? I will be analyzing the chances of the known prospective candidates throughout the week.