@forevrared
In theory, if things progress as they are now, you can see a moderate left, Warren-like technocrat win a Democratic primary in a few decades.
But:
1. The Democrats have shown they can win on massive turnout without a campaign and without talking policy.
2. The Democrats' base is shifting to suburban and wealthy areas, the traditional Republican base. These voters turned out in huge numbers in the primary. They either oppose leftist ideas or can be made to do so by talking about taxes.
3. Depending on the area and ethnicity you are looking at, younger minority voters (who in theory should be the base for the Left) are either voting less or have switched sides.
4. There is no central organisation, but a handful of overlapping ones with little/moderate influence (Justice Dems, Our Revolution, and the DSA in the big cities).
5. Bernie had recordbreaking grassroots donations and recordbreaking volunteer support, exceeding Obama, but could not increase youth turnout nearly enough or win enough existing voters for the primary.
6. A well-designed student loan bailout or a compromise healthcare bill that slightly reduces the uninsured will *kill* the left as an electoral force, and some moderate Dem is going to recognise this, and failing that, maybe a Republican will.
7. Not going to go into detail on this one, but the centre has shown it can drum up identity-based backlashes to leftists among young college-educated people.
8. The role of the media - hard to emphasise this one. 10 days of negative Bernie coverage (starting a little before Nevada) and a week of positive Biden coverage (starting a little before SC) made a massive difference. The Democratic base trusts their media, and CNN/MSNBC/NYT are
amazingly hostile. I keep thinking back to my personal experience canvassing in mid-February, when Biden wasn't mentioned *once*, we heard Bernie a lot, and some Petes and Warrens, and that area went to Biden with 60% of the vote.
9. Climate change - the window for that was exceedingly short and is now lost. Who knows how politics shifts after that, and how much it matters anyway.
There will always be another Trump to discipline the base into voting for soggy oatmeal, there will be the same Obama to call up the contenders and tell them to stand aside for the chosen centrist, and there isn't a Bernie who has appeal among independents (the Squad don't).
The chance is gone - in retrospect the best shot was 2016 when he had amazing approval numbers from independent voters, Trump was the historically unpopular challenger not the moderately unpopular incumbent, and Hillary was disliked by a solid portion of the base- and I'm not sure when it comes back, if at all.