The DNC is a sunk cost. Time to move on.
Showing up to primaries and reforming the party seems infinitely easier in a FPTP system. The parties are pretty much part of the electoral infrastructure at this point, you simply can't "go around" them. Their form can absolutely change, as can leadership, but it will take literal generations to supplant them.
On the other hand, if the people that usually stay home or preach that "the process is useless" showed up to primaries and threw more of the old guard on their asses we could actually have a shot at getting a party to represent working class people. It's the exact same work, there's just less of it because you already have a base of voters.
People can complain about the DNC all they want, but until they show up they're getting exactly what they've asked for. We have the power to clean house.