Step 1 is already done, and now institutional resistance from inside the party is the problem. So it is in fact time for step 2, there’s enough of a body of voters to start building it.
The trick is that to subsume the DNC in the next ten years or so, the party has to form a coalition with it for now while remaining separate. That could achieve two goals: first, put a lot of pressure on Republicans they aren’t ready for. Next, create a strong leftward tension that just isn’t represented right now and which the Democrats will be walled off from controlling.
It’s sort of what happened with the Tea Party / MAGA.
:)