I would argue Bernie ceased to be useful by around March 2016 if his entryist experiment was even necessary at all (I would argue it wasn’t, since the Jesse Jackson campaign is still within living memory). We wasted at least four fucking years on this shit.
Bernie did a lot of townhalls and streaming in those 4 years covering the plights of everyday americans. His primary performance was not how I’d hoped things would go down, but he still helped radicalize a lot of typically non-political people in that build up to 2020.
Bernie could have done all that and not reinforced false hope in reforming, taking over, or splitting the Democratic Party. These townhalls could have been useful if it were in service of directing workers away from the Democrats and towards the beginning of an independent working-class party. But he didn’t, and people are now awake, demoralized, hopeless, and fucking miserable, rather than awake and ready to fucking fight the ruling class for their rights. Shitty leadership is almost as bad as no leadership. Raising working-class consciousness is only the first step, and Bernie did fuck all to sustain any momentum after bowing out in 2020, even taking a reactionary position against the demand to defund the police when BLM came roaring back. He left the DSA to fucking do that for him, and their leaders are just as worthless as he is.