One card to rule them all
with the addition of a small nominal fee per swipe eventually there could be one google bank to replace them all as well.
while i'd like to see the 'too big to fails' get run into the ground and out of business for their intentional misuse of gramm leach bliley act pot smoker slippery willy clinton signed into law despite out right objections back in 1999 from his own party about corporations willfully repeating the 1930's greed and expecting to profit from it thanks to FDIC laws.
after seeing those banks profit from it 3 times in new bankruptcy laws bush signed in 2005 to protect creditors with mandatory repayment, insurance payments and FDIC bail out as well as the government bail out and getting the properties back from the government for pennies on the dollar of all the toxic loans they made and unloaded just so they can start the whole process over again with new victims.
if i were google i'd want to get in on the legalized manipulation and theft too! what better way to start that than with google wallet even if google doesn't charge a fee they can start matching hard actual purchase data and spending habits to web data they collect thru browsing and that data will be worth almost every penny held in a bank.
at such a point they accumulate enough money from this i really believe google will start their own loan/bank system.