Conservative media will go after any Democrat candidate, that's preaching to the choir. Same way it makes no difference what MSNBC says about the Republican candidate.
My instinct is that the way to victory is in picking up apathetic, disillusioned or angry non-voters or rare voters, not flipping the most of the lukewarm purple centrists. And that's true for both parties. Drain the swamp, however you package it, is the easiest path to victory for either side.
Biden won because Obama nostalgia and Not-Trump. However, the Not-Trump effect will be weaker after a 4 year break from the Orange God. I am not sure how much Obama nostalgia there will still be around in two years, but probably still a non zero value. If Dems run some bland corporate centrist like Klobuchar or Buttigieg or Newsom, it will not work. Throwing the election would be a Harris-Newsom ticket, what a perfect storm of soul-sucking anti-charisma and pretentiousness. That would be the Democrat equivalnt of Romney-Cheyney.