Depending on why I couldn't play videogames anymore. If I was in your position where my eyesight had been considerably worsened, I might turn full-on into Let's Plays (but I'm already big into that so it's not a big deal). If I still had cognitive functions and a way to type, I would likely start working on all the novels I've wanted to write over the years. As it stands, my progress on those is really slow because of all the time I spend playing games XD
I also do a lot of kung-fu, so who knows, maybe I'd devote myself fully into that. Again, videogames cut into it at the moment.