The fly in that ointment will be the number of fast food customers who are too illiterate to use the kiosk.
My prediction is that food costs soar, due to waste generated by a spike in customers placing incorrect orders.
Actually, the kiosks will probably show pictures of the food and no words.
For example, a meal deal with a large fry and large drink, will show a large drink, large fries, sandwich and the international standard for arrows will be used navigate from page to page. The tricky part will be paying but most people can swipe their card — just flash a picture of a credit card. Cash might be trickier.
It should be fairly idiot proof.