When/If a code is released for North American systems, you have to input that in the e-Shop.
Bonus: In the demo there will be a mega-evolution that hasn't been revealed yet that we can get! All we need to do is transfer it to PokeBank then transfer it to ORAS!
Yes, there is a new Mega Evolution but you don't need Pokemon Bank.
Clearly in this picture it is stated that the Pokemon can be transferred by Pokemon Link, which is an option in the menu where Mystery Gift and Continue appear.
So to sum it up, we don't know when NA will get a code, but they most likely will.