Actually, this is why I think Square is so well positioned. They're offering a full suite of merchant services, from payment processing to loyalty program mana

Actually, this is why I think Square is so well positioned. They're offering a full suite of merchant services, from payment processing to loyalty program management to proximity advertising, and there's nothing stopping them from joining the coupon space if they were inclined to do so. To lock in the vendor that doesn't want to deal with multiple companies, I think you're going to have to provide a lot more than occasional access to an email list.