From a neutral perspective, cause I've had no leanings towards either of the two leading up to today, there is both good and bad for Democrats with this. The good is that many voters don't like Trump but were also leery of voting for Biden given the obvious, so many might view it as a 'anyone but Trump' sort of situation, which could prove beneficial for Democrats. The bad is that the leading candidate is either Kamala or someone less well known (i.e. governors of Cali/Illinois) who hasn't been on the presidential trail. That said, anyone selected will probably prove a better debater.
The bad for the country is that the left just subverted “democracy” again. If he isn’t healthy enough to run, then he isn’t healthy enough to serve. You can’t have it both ways….
And….