I am curious as to how this works.

Wife and I are flying to London in 3 weeks on supposedly a 787-9p in J

american needs 9 when they only have 8 so I’m guessing there is a chance for a swap to a -9 with less J seats etc.

If we get downgraded can we wait until J opens up even if next day?

Not wanting to fly premium economy from Dallas to London.