While mobile payments are definitely far from being mainstream, the person who makes it possible for all of us to leave our wallets at home will definitely score some gold.
Right now, the market is super fragmented with Square, Isis, Google Wallet, and then branded options like the Starbucks app. At this point in time, if you were to leave your house without any cash or credit cards, chances are you wouldn't get too far.
But as soon as one solution wins as the be all end all for digital payments, wallet makers beware.