If Biden died on November 4th, he'd remain on the ballot the next day and - if he won the majority of the EC - Harris would be the presumptive President Elect on November 6th. If Vance resigned as VP, we'd see the same results under a Trump win. We have a clear order of succession and mechanisms for appointing replacements to downticket slots like VP per the 25th amendment.
The absolute worst case scenario is that Trump would force Vance to resign and then be stuck with a House/Senate picking his VP for him. But since he's not even the President-Elect at the moment I don't think that's actually an issue.