Waiting this long certainly hasn’t helped him, whatever he decides to do.
If he does run, attention will focus on the signs that he was preparing all along but waited to see the shape of the race. Reporters will seek out some Democratic operative who moved to Washington because she had been promised a job in the campaign policy shop, or examine the donors Biden called on the q.t., or lay out all the detailed groundwork of his innermost circle.
If he doesn’t run, expect his inner circle to leak stories about how earnest and serious he was about entering the race. But there will be lots of reasons not to believe them. People will look back at all the things he did not do, such as call key members of Congress whose support was “gettable” by their own description.
Either way, Biden looks less and less like a father stalled by grief and more and more like a manipulative politician. So in that sense he has already lost, no matter what he decides.