I don't think he has to actually die to be replaced. He supposedly has COVID again, to that might be the excuse for him to "step aside" from running again due to a "serious medical condition". I think there's a fairly good chance that he'll step aside from running for the good of his party, but no chance that he'll step down for the good of the country.
“but no chance that he’ll step down for the good of the country”
************
And so for the next 5+ months the country will not have a functioning president or a decisive Command-in-Chief. Its all too obvious that Biden is simply incapable of managing any kind of national crisis.