I think you'd hard put to show any evidence of popular support of policy and political legislation. Public support has had almost no impact for decades now. Capital on the other hand....
So since the "whats your plan?' question has been made as a qualifier of the accuracy of observation and criticism of the existing political situation, I'll have to ask you again, what is the plan?
Admittedly, I agree with allowing the Democrats to hang themselves but I don't think It'll happen in 2020. They'll run a "We can't afford 4 more years' and push Biden out in front of voters. No ideas, no solutions to some of these overwhelming problems. Trump wins. May pick up more in the house. But I draw your attention to the imposed obstacles of electing progressives.
I don't see how 'give em enough rope' will make any change within the Democratic party with the current party structural situation.