Most already carry Smartphones. Having something like this would be useful more in helping to train those who need the extra guidance when they start learning how to adapt to being blind or even in therapy or the classroom to help with a unit that allows them to read the news in Braille. When someone is blind and relying on their Cane to help them, along with Seeing Eye Dogs. There is already Smart Canes out there.
I could see something like this useful if they have an app or use a Smart Cane and it triggers the Cane or Smartphone App to describe what they are in front of, or even for when someone comes to their door and the camera triggers the Pi to trigger an announcement that someone is at the door. A Peephole camera is all that is needed. Same with using voice recognition to turn on or off items in the household.
Ren: Now listen, Cadet. I've got a job for you. See this button? Ren: Don't touch it! It's the History Eraser button, you fool! Stimpy: So what'll happen? Ren: That's just it. We don't know. Maybe something bad, maybe something good.