re: The Democrats will announce a different nominee in Chicago

They can't. Biden has to step down or the 25th needs to invoked which requires 2/3 vote. That won't happen because conservatives want him on the ballot. And no, not every state has write in candidates. I think there are 2 blue states that straight up don't allow write in candidates.

Biden is the candidate unless he drops out or the 25th which means he is the candidate. I don't think anyone in his family can convince him to step down because I don't think he has the cognitive ability to see he is not in great shape.