A thing that doesn't usually change (although it is not unheard of) is the number of floors in a building. If I were to design a modern elevator interface I'd

A thing that doesn't usually change (although it is not unheard of) is the number of floors in a building. If I were to design a modern elevator interface I'd probably go with backlit physical push buttons and small screens next to it. This way you can communicate disabled floors, what you find on each floor, etc. The push button light (brightness and color) can be used to indicate the current floor. The push buttons still need braille for the floor number tho.