intlcaptain
It is even totally possible to gravity drop landing gear on nearly all commercial airliners, I would expect, though I can only speak on the types I’ve rated on. I don’t see you asking “what happens if the landing gear lever fails?” which is actually a totally reasonable question, and one manufacturers have thought of. Touchscreens aren’t magic devices, they’re just another type of input to build redundancy behind.
It sounds like a horrible idea because you probably haven’t flown an aircraft and don’t know this. That isn’t an indictment of you, just a request to not judge so soon. I like the idea of screens that adjust to phase of flight so what I need is where I need it, because pilot workload is a real problem that automation has addressed for decades.