The only thing that could conceivably provide a systematic opening to fix things (ie, not just fixing specific things, after they've become apparent, because they've already catastrophically failed), in the realm of badly-written science fiction and fantasy, would be:
Bernie Sanders (or another equally popular candidate, in the near-future) is ratfucked so badly and obviously (which this could be the start of the perception of, even if it is just sufficiently advanced incompetence to be indistiguishable from malice), then the nominee loses to Trump so convincingly, that it completely shatters the party -- like it is no longer able to function at a basic level, and will clearly, even to the most delusional, never be able to win another election again -- and then... something, I don't even know how this would work. I am not creative enough to write this laughable science fiction any further.
There might also be a route involving Bernie Sanders winning both the primary and the general by a landslide, but that comes with its own and different set of systematic problems that I don't think would make the party's competence at dealing with technical problems, at least, any better.
But in either case, the deepest underlying rot is still the toxic interests of its financial backers, which are reproduced in the very bones of the party, and occasionally pop up in especially ridiculous and very indirect ways like this (and many more that don't get frontpaged as a problem on HN, or the New York Times for that matter). There's no fixing anything without somehow getting rid of them. And there is no realistically traversable path to that.