The change just aligns them with Delta's policy (more or less).
On that subject, the SkyMiles rules say
Delta and its program partners reserve the right to change program rules, regulations, Travel Awards, mileage Award levels and special offers at any time without notice.
I would like to quote from Northwest's rules, but they are more elusive. I think confusion may arise because most of the programs say they will give 3 or 6 months notice of termination of the program.
[This message has been edited by james (edited 10-08-1999).]