There will be a brand new reward card in the Cash Shop on October 15th. That means the current card, along with its prizes, will be retired at that time as well!
Remember that you earn stamps on your card for each 1000 credits you purchase through Paypal or Stripe. These purchases do not have to be all at once!
Ehh stuff gets retired all the time. The same can be said for bobbleheads - new users didn't get a chance to complete those.