If not, what would it take?
A viable third party candidate. Before anyone says it, Jill Stein is not it. Alternately, a voting method that allows voting third party without just enabling a GOP sweep (again).
It'd be great if this resulted in some major revision of the Democratic party from within, but I'm not holding my breath. I will, however, continue voting for the "less bad viable option" if the "more bad option" is on par with Trump.
It's about who has a chance of winning. If you're trying to argue that any candidate other than Harris had a chance of beating Trump in this recent election, you're kidding yourself.
I've said this before and I'll continue saying it: Trying to inject a 3rd party candidate into the presidential race is foolish. A much better tactic would be trying to push for 3rd party candidates in smaller races for local / state government, or congress. Doing that is a lot easier, and can make small incremental changes that add up over time. There simply isn't a realistic way for a third party candidate to compete in the presidential race until the voting system is changed.