For Sanders in 2020, I would tell him to:
-Reach out to black voters more (especially older ones)
-Go after his primary opponents as aggressively as Obama in 2008
-Focus more on the “electability” argument more
[He didn’t have to change his stances on the issues; he just had to frame his arguments in a different manner.]
Yeah, I never understood why once the race was down to just him vs. Biden, why he didn't attack Biden much harder and make more of an effort to turn the electability argument in his favor (He could have compared Biden's history, policies and campaign to Hillary who had already lost). I don't think that Bernie had any chance of winning the primary once the establishment united around Biden, but I think that Bernie could have at least made it closer post Super Tuesday by better going on the attack.
The reason he didn't attack Biden much harder & make more of an effort to turn the electability argument in his favor is because he understood what you yourself noted: that once the establishment had already united around Biden (in combination with the fact that the default outlook in the remaining post-Super Tuesday states like WI, MI, IL, FL, GA, LA was just really bad for him), he really had no chance of winning the primary. At that point, his campaign - almost by necessity - really had to stop being one which could win so much as one which could amass as many delegates as the circumstances allowed so as to ideologically influence as much of the party platform (& thus Biden) as possible.
