i suppose there's still an opportunity to reshape the actual party members.
but, so long as the actual people voting in the actual primaries are the same old democratic primary voters, it's hard to see who is going to challenge biden for the centre.
see, and whether that centrist voting base kills them in the general or not doesn't negate it's existence. if these swaths of general election voters can't cast ballots in the primary, they may never get to cast their vote for who they want in the general. as a result, trump may win again, sure. but, you're never going to get this across to them. biden's the last old guy out there, the last member of the generation of leaders they recognize.
so, this isn't a debate about tactics - it's a reflection on voting demographics in the primary, and a realization of how different the primary is than the general.
biden is still winning. comfortably.