i just want to add an after thought to this bernie sanders running again thing.
i pointed out that the left may be looking forward to 2024, and that if an acceptable candidate doesn't present itself then bernie becomes the option by default - as a protest against the democratic party. that said, the best tactic may be helping bernie build a movement, anyways.
you also have to keep in mind that trump is, himself, also an old man. if the argument is that it's irresponsible to support a candidate at such an advanced age, that may be blunted by the reality that there isn't another choice.
so, if there is no viable candidate anyways, there is no harm in focusing solely on the future; while bernie himself may never enter the promised land, he might help lead us there.