The delegates are also a problem if Biden doesn't go willingly or die. They're bound to Biden and there are rules in place to replace them if they were to vote for someone else.

If Biden is swapped out, only Kamala has legal right to use his war chest.

My understanding is that Kamala just has to be on the ticket. So they could theoretically keep her in the VP slot and replace Biden with say Big Mike and be good to go.