What I'm gathering from your statements, more or less, is that the worst consequence of Biden's loss of political capital is that he will be unable to convince red states and Republican leaders to go along with him. This is a problem for sure, but what makes the current Democrats unique in my view is how dug into their positions they are. No Republican will ever win an election in big blue cities barring a miracle. Most of the people and organizations who are dedicated to supporting the Dems believe that the opposition is pure evil and could never imagine joining them. The posters on Ovarit are a good example, so much complaining about how the Dems are the ones putting rapists in prison with women but most of them still insist they'll always vote Democrat.
What my point boils down to is that many powerful people and groups have inextricably bound themselves to the Democrats and changing this status quo will be extremely painful for all involved. The CEOs and politicans may be Machiavellian, but a large part of the Democratic base think in religious terms. A decade ago things were different, but now many organizations that used to be apolitical have taken a hard ideological line and backtracking will cause their followers to mutiny.
Perhaps what this means is that Biden running out of steam politically will make violence inevitable. There's already a soft secession going on of Republican areas that won't enforce COVID mandates, and if their disregard of authority keeps going eventually there'll be no option but to use force to bring them in line. The political left looks to me like an army marching with guns to their heads. The local Dems who helped stuff the ballot boxes in 2020 will likely work harder at it in 2024 because they'll be fearful of losing their jobs or being prosecuted if Republicans get back in. Even if Biden completely runs out of good will and favors they'll fight for him on an empty stomach due their fears, both realistic and exaggerated, of what the other side will do if they win. One last-resort tactic for them could be to remove Biden via the 25th, blame everything bad on him and run either Kamala or another token minority who's protected from criticism by the race shield.
Do you live in an area that's red, purplish or solid blue? There's a big difference in the behavior of liberals in places with some diversity of thought and places where they're a supermajority. The ones who live in a sealed blue bubble often think that anyone to the right of them must be a demon spawned from Hell.