It's in a companies interest to make sure that there is a way to give them money, they are unlikely to want to throw away good customers just because they don't have a FB account.
What I would expect to see however is discounts offered if you use FB payments and allow your purchases to be automatically shared with your friends.
allow your purchases to be automatically shared with your friends.
This is one of the creepiest feature one can get. I already hate these social readers which automatically share what you read (I've stop reading stuff on FB because of that, even if many of them are of my interest). However I'm hoping they would provide some reasonable privacy options with that.
What I would expect to see however is discounts offered if you use FB payments and allow your purchases to be automatically shared with your friends.