See inside what? Did you link to anything?

As I see it, key deadlines are:

• The party conventions, where each parties nominee will be formalized. (But recall that the actual Democratic Nomination will be done before the convention, to meet some State deadlines).

• The election itself, where voters choose which slate of electors cast EC votes.

• The electoral college election that really matters.

• The counting of the EC Votes

• the inauguration

Once the nominations are formalized, they probably can’t be undone, since there are State deadlines involved.

But always remember that people are not voting for the candidates themselves, but for a slate of electors. And while the expectation is for these electors to vote for the ticket they were pledged to, if one candidate is subject to God’s Almighty Recall Vote, they appear to have the discretion to file votes differently.

Once the EC votes are cast, though, there would probably be no choice but to accept them. (Congress recently revamped the counting process to eliminate some of the shenanigans that happened last time). I expect that if either one croaks after that, they would probably just inaugurate the VP on the ticket directly.

(Edited to add: states may be able to change EC votes after the December EC election. That date is based on a “safe harbor” deadline which makes EC votes harder to challenge. So, if the winning candidate bites it on Christmas Day there’s probably a way for State Legislatures to certify new EC votes before Congress counts them Jan 6, but we should expect a challenge to that.)

(It would suck if Trump won, and Biden croaked on Jan 19th. We might have our first female President, for one day.)