Do keep in mind, though, that of the "billions of people" who use credit cards, the number that use cards that can be cloned by reading the magnetic stripe is fast dwindling. Until/unless Coin gets cosy enough with the card associations to the point where they can get some way of cloning chip and pin cards (EMV), they're DOA in a quickly rising list of countries that already covers the majority of the developed world.
And a large part of the point of chip and pin cards is that they're meant to be impossible to clone. E.g. in France it supposedly cut card fraud by about 80% for in-person transactions. So unless Coin can convince them that it will be as secure or more secure than these cards, they're going to be pretty much limited to the US, and increasingly get marginalised in the US too: Most large US banks have announced rollout plans for EMV cards (though many will be chip + signature rather than chip + pin).
And a large part of the point of chip and pin cards is that they're meant to be impossible to clone. E.g. in France it supposedly cut card fraud by about 80% for in-person transactions. So unless Coin can convince them that it will be as secure or more secure than these cards, they're going to be pretty much limited to the US, and increasingly get marginalised in the US too: Most large US banks have announced rollout plans for EMV cards (though many will be chip + signature rather than chip + pin).