Originally Posted by
diburning
Correct. The fare class does not change if you change flights.
The value of your ticket is what you paid for it, not what it's priced at now. If you want to sit in Mint, you will either pay the fare difference between what you originally paid and the current Mint fare, or you can buy up at the gate for a flat fee if there are any seats left by then. You will not be have the option to pay for the difference after the flight goes to gate control.
To make this clear to myself:
Due to this wording on Jet Blue:
Mosaic members and travelers booked on a Blue Extra fare can make same-day switches for free. (That’s no fee, no difference in fare.)
If you book a flight for $200 in Blue Extra.... on the day of, you could switch flights to a $1,000 Blue Extra fare. It would cost me $0.
Now if Blue Extra is $1,000 and Mint is $1,500 for this new flight.....
I could not just pay $500 to 'upgrade', I would have to pay $1,300 to 'upgrade'? Sounds strange.