The left's base is not homogenous; I'ts made up of many factions, divided along religious, ethnic, and lifestyle lines. All vie with one another for priority within the party (black vs. Hispanic, feminist vs. trans, union workers vs. illegals, etc.). All want the biggest share of attention, the most clout, the biggest piece of the pie. Some or most are in direct opposition to each other.
The DNC has done an exceptional job of keeping them on the plantation up to now, but it shouldn't surprise anyone to see some groups slipping away (young males and some traditionally democrat-leaning unions, for example).
The MSM plays up the MAGA/RINO schism within the GOP but it could be the DNC that splits into warring fragments.
The Communists are too extreme for the average American voter.
Get rid of the Communists and all the Academics. Then they can appeal to everyone once again.
But I don't see that happening because right now they are the two major factions in the party (and they sort of overlap with each other).
There are other factions in the party but they are not influential at all. You have the Union Bosses but they have no power because the rank and file voted for Trump in the past three elections.
Blue collar private sector union workers-moving to the Republican party. Union leadership not so much but maybe slower.
Government union members and leaders-still an important part of the Rat Party.