I don't think anything is holding it up, per se, outside of what David was saying about the migration in Canada to NFC and mobile technology.
But I think you're accurate, in that as a consumer you might have your MasterCard, Visa, Interac, Diners Club, JCB and American Express cards on your mobile phone. You would make a choice the same as in the physical world, where you pull out of your wallet whichever card you want to tender for the sale. Then the transaction is completed with the payment card you choose.