So where we at?
1) Biden still in but seems to be adjusting his criteria somewhat already for dropping out from only god can tell him to well if the polling gets worse essentially. This may undergo more adjustment as circumstances dictate (political support, fundraising, feedback from his allies). His campaign is implicitly writing off states that are not WI, MI, and PA so we are back in the much dreaded "blue wall" strategy territory as the primary hope for this to get pulled off. Certainly plausible but not exactly what I'd call reassuring.
2) Trump for his part thinks he's already won when his national lead is less than half of what Hillary enjoyed at this time in 2016 and arguably after the best news cycles for him in recent memory. Popping the cork with months to go feels unwise but he's never had a surplus of that to say the least. Trump veepstakes still ongoing but nobody really seems to care. Vance appears favored but who knows. There is a chance their conviction that Biden must stay in at all costs could ultimately backfire and the shit is absolutely going to hit the fan if Trump is leading him in the polls going in to E day but its looking like he loses as the vote comes in.
3) If the switch happens it is abundantly clear he will endorse Harris. He even noted the practical hurdles to anybody else trying to step in at this point like the campaign war chest. Glowing praise for her when asked about her ability to do the job and confidence in her. This also could be in part a judgement that if he has to step down for health reasons in a 2nd term that the country would be in good hands.