CO program runs like most other airlines from Feb to Feb,
with miles accumulating Jan-Dec. Although I am not sure,
so take it with a grain of salt, I would think you would
get new cards after Feb reflecting an expiration date
of Feb 2009. At this stage all cards expire Feb '08. Of
course easiest is to give them a quick call. Then you
would know for sure.
Interestingly enough, if you "re-qualify" for Gold before
Mar 1, 2008 you actually would be a Gold until Feb '10.