The downside of doing this is that, If you have to cancel your delayed flight and it’s been a year since purchase, you will likely forfeit the ticket. If you rebook it immediately, that might not happen.

I had this happen on AA. for legal reasons, I had to book a flight in advance (9 months). had to cancel, but did not immediately rebook. went to rebook 14 months after purchase date and credit has evaporated. (