But with mobile payments, you need a bitcoin accepting merchant.
Whereas with bitcoin debit-card, once your card loaded with funds, you can spend you bitcoins to any merchant.
Mobile payments does not require any third party. Our bitcoins will be with us always.
I guess bitcoin debit card will be the first one to boom, then it will be followed by mobile payments once there are many bitcoin accepting merchants around the globe.
The point is, is that you could be able to load and store value of your bitcoins on a debit card to use anywhere by converting it to fiat upon a purchase. Although, I'm not quite sure if there is a debit card system that actually holds bitcoins until you make a purchase. I think when you load a card, it's automatically converted to fiat.