[kenshaw]

Purpose-built robots for things like "making sandwiches" will always be cheaper than general purpose robots. There really isn't a culinary task today that can't be fully automated (you can look at the frozen food section of a grocery store for examples of almost every cuisine type). The reason this hasn't happened at your corner diner is that manual labor remains much more inexpensive in the short and long term for low volume production (ie, restaurant vs food factory). Additionally, before it becomes cost efficient to build a customized culinary robot for a restaurant, it is still less expensive to design a custom culinary tool for use by the human staff that will net 99% of the efficiency of the purpose-built robot.

Barring "replicators" (a la Star Trek), or labor costs rocketing through the roof (perhaps from something like a "minimum income") I don't expect the general composition of restaurant staff to change in the next hundred or even two hundred years.