The democrats and Joe didn't do themselves, or the country any favors by allowing him to continue with his obvious outward cognitive decline, that seems to be true. There wasn't a collective effort to push him out, as he'd been a steady leader, had defeated the felon in 2020, and so those that that were understandably concerned, had to keep their powder dry, and hope Joe would himself recognize his own condition, especially after the disastrous June 2024 debate. By the time Joe took the correct course, it didnt allow time to "elect" someone through an inter party process rather than just install Kamala, which seemed undemocratic to those that criticized that decision, and there could have been more acceptable candidates to the electorate. That she is a black woman likely also worked against them, as the pervasive theme of racist, misogynistic ideals still seem to be fairly entrenched in American society still to this day. Look no further than the republicans attacks on DEI that they still trot out as principled ideas, that are merely more racist, and misogynistic ideals they use to divide the country, and further their white nationalist agenda.
The country punished the democrats at the ballot box, but fell for another song and dance from a convicted FELON, that deserves, and has deserved all the shit slinging, and much more(Judicial accountability for one). That the "Nazi" label has been applied to this president and his administration is quite appropriate considering the undemocratic method of governing (bypassing a co-equal branch of government in congress), and the attacks by the executive on the other co-equal branch (the judiciary), and so many other actions already taken against immigrants, denying them due process, and shipping them off to an El Salvadorian gulag. And they arent finished targeting immigrants, and likely wont stop there. I mean look no further than Elon and his "Nazi" salutes. Likely meant to "own the libs", it also reflects his beliefs, and he seems to fit right in with this leader and his hand picked administration.
Now that the felon is tanking worldwide opinion of the United States, and destroying the US economy and "the deep state", lol, which is really just the government in essence, will certainly open opportunities for democrats. They need to capitalize, but you are correct that they need viable candidates that can offer solutions for the people of the country. They will first be tasked with repairing the colossal damage this administration has wrought in just a short time back in power, and the damage that undoubtedly will increase for the duration of this term. I doubt we'll see another free and fair election though, so the country and the world indeed will suffer, maybe indefinitely.