Interesting observation by VFTW,
Buried in the card details, though, is this clue about the future of the combined United/Continental program:
Your miles don’t expire* Your miles don’t expire as long as you are a Cardmember with no limit to the number of miles you can earn.
Continental miles didn’t expire. United miles expired after 18 months of inactivity. This tidbit means that the combined program will have expiring miles.