Take heart: the right (who were going to vote for him anyway) are loud in their support for Trump's "martyrdom", but has his shaving-cut really brought a single independent voter over to his side?
I'd say that his subsequent anti-Democrat rants, after his touching appeal to be less adversarial as written by his advisors, have probably lost him more votes than he gained by pretending moderation.
And I don't think there is a candidate who would a] take the job at this late stage in the game, rather than start to work towards 2028, and b] polls better than Biden against Trump. Even if they could get onto the ballot after the primaries are over, which in some states I have a feeling they couldn't. So it seems likely that option is a non-starter.
And after all, what has actually changed? Biden has still done a cracking job as President and helped a shedload of people, same as he had this time last month.... and Trump is still demonstrably deranged, suffering from word-blindness and an inability to remember names reliably, and continues to be unfit for office....