To follow up on my own post, I called BofA to ask if my BofA AGR card would become a non-AGR card after 10/23 or would close.
The first person I spoke with said the former, and that I would still have the $79 annual fee on the new BofA card. Well, I don't mind the now-$99 annual fee for an AGR card that I'll use daily, but I want my backup card(s) to be fee-free. So that operator said she'd transfer me to sales to pick a new card with no fee.
The second person said that there would NOT automatically be a replacement non-AGR BofA card after 10/23. The account was being transferred from BofA to FNBO and I would still have only one card (FNBO AGR) after 10/23, not two.
I'm going to presume the second person was further up the customer-service ladder and go with his answer.
It has the virtue of being consistent with the FNBO FAQ: use the BofA card until 10/23 and the FNBO card after.