She would have lost, even by the DNC's own crappy poll metrics which showed several candidates that were much more popular, like Newsom who could have easily fulfilled his role as a shill and a well received candidate instead of just an obvious shill.

DNC running around with "too late for a primary" and "can't adjust voter law" is moot when you consider that almost all of them have a catch all cause for holding primary elections in circumstance, and the fact that they aren't even tied to the Federal election or even State control if the DNC wishes.

That all being said, Harris would have been the de facto candidate as the incumbent if Biden died, but if the DNC wanted to, they could easily chose not to run her as the candidate and hold a primary.

Your question isn't relevant to what actually happened because it's an entirely different hypothetical situation.