It looks like Google will soon be removing some functionality from Wallet. The details come by way of an email that has recently been sent to Wallet users. Or specifically, to Wallet users that happen to have added a gift and/or loyalty card to their account. Basically, support for these cards will be going away as of August 21st.
With that in mind, those cards will not necessarily become junk. Google has said the support for these cards will end in Wallet on the 21st. If you happen to still have the physical card available, the balance will remain and you can continue to use the card until the balance runs out -- even after the 21st. On the flip side, if you no longer have the actual card -- you will want to get to spending because it is becoming a use or lose situation.
On August 21, 2013, we are ending the current NFC redemption of gift and loyalty cards added to Google Wallet. If you've already redeemed your gift cards, you don't have to do anything. If you have a balance remaining and you'd like to spend it using the tap and pay functionality, you must do so by August 21st. If you still have the physical gift cards, they will continue to work even after August 21st.
Another point worth clarifying is this change deals only with gift and loyalty cards and will not affect credit and debit cards. While this may sound like a not so good move for Google Wallet, it does appear as if it may only be a temporary measure. In that same email Google went on to talk about how they are already "working with retailers on other options for gift and loyalty card redemption within Google Wallet."
More to that point, they have said they are excited to share those details "soon." With that in mind, those with a gift or loyalty card (who no longer have the physical card) may want to start planning some purchases.