PayPal is doing a copycat on Square with its card dongle named PayPal Here. The transactions is said to be 0.05% cheaper than Square..but still very expensive I think (2.7% on the purchase value).
Even though this is not mobile payment (it´s a mobile card terminal) I really believe that mobile payment will have the liftoff when it’s easy to use, available as a method at POS (and many places!), online (could also help secure these purchases though mobile is a good security tool), vending and P2P and is cheaper or equal as a card purchase.
These mobile card readers (using the stripe) will only work in US and I don’t believe they will be the solution, but a bridging one until “the solution” or better mobile technology standard for mobile payment appears…and NFC could be part of that.
See how PayPal’s mobile card reader works here.