I think Biden has a chance and I hope that he does win but he has two major issues that might sway the election towards Trump:
1. His being seen as senile or starting to have dementia. Both candidates are far too old for my liking (for the most important job in the world why are our options two guys approaching 80? How in touch are they with the modern world?) but people are worrying about Biden’s mental capacity rightly or wrongly and if he has dementia and he has to disprove that. Personally I don’t think he does, I just think he’s 77 and like most people that age isn’t as quick and sharp as they used to be. Trumps loud mouth seems to overcome that hurdle for him although he may be suffering the same we just don’t see it, but Biden absolutely has to prove that his age isn’t an issue.
2. The riots and "peaceful protests". He’s been delicately dancing around the issue but every night there’s pictures of people burning down buildings, teargas, hurling rocks, guys shooting people vigilante style, CHAZ, the idea of defunding the police, and just general chaos. This doesn’t help Biden, the center will move towards Trump (which is odd because Trump more than anyone else throws fuel on that fire) the more this keeps occurring. Biden will need to reassure voters that when elected he can somehow help to resolve this and get things back to being peaceful.
I have no idea if he can convince voters (and the center in particular) on these two. To do so he’ll have to be seen though and right now his campaign seems to be drowned out by other events happening. The biggest stage to do so will be debating Trump. If he backs out of that for any reason it will be a death knell on his campaign and all but assured 4 more years of Trump.