It's been kind of subterranean, but the Democratic party has been sort of stuck in the middle of a potential realignment for years now, basically since 2016. After the disastrous Clinton campaign, the DNC underwent reforms to reduce the importance of super delegates and the party saw a surge of progressive activity. Things have basically stalled out, with the party in a kind of dysfunctional holding pattern through a combination of operative groupthink and elite panic as they don't really know how to move forward from where they are. The DNC is a machine made entirely to preserve itself as a functionary to institutions that it paradoxically can't protect, the Democratic leadership lacks the political understanding to safeguard their own power, but a lot of them have a sense of how fucked they might just be. This all got pretty real for them when Paul Pelosi got attacked, at least as real as they're capable of understanding.
If they lose this election, I think that they'll try to realign rightward. If they win this election, Biden's old school coalition of labor, environmental activists, civil rights groups, corporate interests, and disenfranchised conservatives will be vindicated to some extent, and that very tentative alliance may be preserved.
The Biden administration has been, among other things, a rebuke to Clintonian post-Reagan politics. The Biden presidency has been, in essence, policy reform presidency; not reformist towards changing systems, but reforming the policies and activity within those systems. That makes for an extremely fragile and personality based kind of reformism, but the scope of the policy differences is hard to overstate. The new regulatory posture is aggressive, the kind of regulatory policies that have been adopted are basically unheard of since FDR, the bully pulpit has been lent to union leaders, all sorts of stuff. But a huge amount of the Biden administration's efforts can be undone by replacing personalities, reversing executive orders, dismantling agencies, etc; a lot of it is very fragile because of of Biden's institutionalism and refusal to even go so far as to consider reforming systems rather than just reforming policies within systems.