Not true
if trump is the boogeyman everyone says he is the democratic party can throw out a Newsome or Whitmer and anti trump voters are not gonna give a fukk because 1.Most people want a younger replacement anyway 2. It’s all about anti trump
biden was never somebody the majority voted for …he was always the anti trump vote
this isn’t like someone Widely loved like Obama getting replaced
What you're not understanding is that you can't bet on people supporting Biden to suddenly support Newsome or Whitmer just because they're democratic candidates going against Trump.
People have their reasons for why they support Biden, as you said yourself some voted for him simply because they wanted Trump out but, then other people voted for him due to (believe or not) his policies, agendas, etc among other things.
There might be Biden voters who don't like Newsome or Whitmer's policies and agendas so you can't assume they'll just vote for them.
All Dem voters aren't the same or think the same way. You'd be taking a gamble thinking that the support for the aforementioned candidates would be the same as the snap of the finger.
That's something you can't afford right now.