You’ve hit on the key point. The Progressive Left is fighting the Liberal Establishment for control of the Democratic Party. Over the course of this struggle, the party has veered sharply away from what it used to stand for. The Left is winning. You rightly point out it has forced the party to effectively disown the legacy of Bill Clinton. Then you take the next step and rightly observe intellectual consistency demands the party also disown large parts of the Obama legacy.
What you don’t address is whether such an action will alienate so many Democrats that Trump wins in a landslide. How popular is a platform of open borders, reparations, dirty cities, extra taxes on gas, attacks on free speech, and legislating against hamburgers? How do you get an electoral college majority to identify with vilification of whites, hostility to males, disrespect of America, and the condescension towards the working class that characterizes the Radical Left?
Clinton empathized with the people and worked to give them economic opportunity and keep them safe. Under his watch, the economy transformed and things got better. People saw their standard of living rise. Under Clinton’s watch, crime dropped and the country became safer. He was fiscally responsible. The country last had a surplus when he was President. Clinton had support from the broad mass of people in the center and had a strong rapport with people of all races, ethnic groups, and religions. He won a huge electoral college victory. That is what the Democratic Party is now ashamed of?
If the party is pushed so far Left it also attacks the Obama legacy, it will be a signal to many the time has come to leave. But really it is the Democratic Party that has left them. The party they once identified with is now far along the road to becoming a popular front for various leftist radical organizations. How many more will join the many who have already “walked away”?