>these folks do realize they are gonna need to win over
>moderate democrats, crossover republicans, and older black
>voters if bernie is the nominee right?

crossover Republicans are not going to vote in significant numbers for a Democrat.

If Bernie is the nominee, and the moderates and older Black voters want Trump out because that's their chief concern?

they'll vote Bernie, period.

But a moderate candidate offering nothing besides "Not Trump" is just gonna repeat Hillary. Possibly worse.

TRUMP is an incumbent, with all the structural support on his side now, unlike 2016. He survived a sham of an impeachment, which he will turn on any Democrat running. It doesn't matter what mistakes he makes. Like 2004, but worse.

You need ALL the votes you can. Going "moderate" in the Democratic way means you're going to lose against something like that for sure. there is no historical precedent otherwise.