I was not able to access my online AMEX balance. It led to a call to AMEX and Atlantic. From Customer Service:

- $600 triggers the 1099
- New AMEX cards being mailed this month (extended expiration date).
- Credit earned (at/above the $200 threshold) does not expire.
- Reward certificates can expire (like Chriss99 said).

So, expect new cards that carry-over any existing credit.
And long live the Atlantic Reward program!