How a socialist/progressive can win the Democratic nomination in the future

[Blue3]

Even if Sanders loses this nomination in 2020, he has pushed the Democrats to the left in 2016, throughout Trump's first (and hopefully only) term, and again now in 2020.

Unless they change the Democratic primary system (which they should, they either need to decrease delegates in safe-GOP states or scrap delegates completely and go only by popular vote and only primaries)...

Both 2016 and 2020 underline the key to a socialist/progressive victory is earning and being the favorite candidate of the South. Sanders made great inroads between his two presidential campaigns, but when it came down to it, Biden was still the favorite. If a socialist/progressive candidate can become not only acceptable to Southern Democrat primary voters, but their favorite, then that candidate will be the nominee. If someone similar to '88 Jesse Jackson were to run again, that person would probably be the Democratic nominee.

Thoughts?