I would think there are a lot of paths to take. McDonald's has already tested the technology of outsourcing their drive through order takers to India. If a fast food restaurant redesigns their space to a drive in like Sonic, where people eat in their cars, it will remove the labor involved in keeping their seating areas clean. Many restaurants have moved their drink machines out to the customer areas because the labor involved in getting a drink is more expensive than the drink itself, so they outsource to the customer to get their own drink.
Bit by bit, the labor can be removed from these companies.
What about those self service cafeterias they had in the 50s? I think we are going to see a lot more automation with an eye towards eliminating checkout positions, and possibly robotic stocking. Just keep an armed guard at the odor to see that things don’t get out of hand.
Iirc McDonalds has the ability to automate every function in their restaurants. They have had it for years.