One problem with looking into the future is most people only think of one thing changing at a time. For instance many people though that as buildings became taller, restaurants and other services would need to be built in sky scrapers to provide basic services. They didn't think of potential inventions (such as elevators) that would simply make it easy to travel back and forth between 40 stories. Many of the tasks you describe feel very similar to this issue.
Did you know that most McDonalds shut down every night, everything in the kitchen is taken to the sink to be washed and sanitized, then put back so the morning crew can flip a switch and start serving customers?
Robots will not use the same dishes and utensils that humans use to make food. For instance it isn't like you use a robotic arm to physically flip burgers on a pan, you create a conveyor belt that cooks on both sides at the same time. The machines built to replace humans will not only take into consideration the most efficient way to cook food, but also the most efficient ways to either self-clean or be cleanable by another machine.
Did you know that twice a week a huge truck comes by, drops off boxes of food ingredients, and those have to be inventoried and stashed properly so they can be used throughout the week.
If only there was a major e-commerce retailer that has already been working on using fleets of robots to make loading / unloading products easier. I'm sure this technology will never proliferate to other industries. [/sarcasm>]
When that stuff comes, the next promotion that comes around has to be deployed, cardboard cutouts assembled, decor changed, etc.
Even if you couldn't accomplish this with digital signs / posters / etc, these tasks are done infrequently enough that a small group of human employees could probably service dozens if not hundreds of stores.
What I'm trying to tell you is that you can automate the cooking of the meat or the dispensing of the shake but you're not removing any significant amount of man-power to the place. You might be able to shave one or two people during the weekday lunch shifts, but until they start making full on androids you're nowhere near minimum-wage motivated store automation.
1) Kiosks taking orders. If Walmart self-checkout lines are any indicator, one human operator with six kiosks could probably replace six cashiers.
2) Machines cooking the food. Plenty of machines already help cook food now, but once again I could forsee machines that reduce three line cooks with one line cook and more machinery.
3) Machines packaging the food. Again you will likely need some human intervention, but this also removes a few staff members.
4) Lower number of employees also means a lower number of shift supervisors.
I could easily see a McDonalds crew being cut by half or even 75% with only today's level of technology. The only thing stopping it is the robots are still more expensive than humans. More engineers would certainly have jobs, but probably around the rate of 1 more engineering job per 10-20 crew member jobs lost.