Stripe is nothing--just a faster horse. PayPal and Square (and Google and Apple) ultimately aim to replace the credit card itself. That's the prize. Square is attacking from the B&M merchant POS side and consumer to consumer email payments, Apple from iTunes and mobile, Google from mobile and web properties, and PayPal from online merchants and consumer (though, in all honesty, I see so little innovation coming from PayPal I sometimes wonder if they see what's coming). I suspect the key is to win the consumer by bootstrapping with physical merchants, so I give the odds to Square, and to a lesser extent Google and Apple.

Apple and Amazon are other potential suitors for Square, but the company is kicking so much ass I doubt they'll sell. For all HN likes to spin acquisitions as victories, 95% of the time they are the final denouement of a defeated startup. When a startup is doing well, ambition takes over and selling is usually out of the question.

>I doubt Google really wants to get into the offline payment market.

NFC payments? Google Wallet?

The financial transactions business will be dramatically different in 10 years from now, Square will IPO to make their big $ back, and then let the public take the blunt hit of the market shifting towards even lower cost transactions. 2.7%+ is ridiculous.