Hm, if you're taking idea suggestions, then I may have a thing. Feel free to ignore me if you've done it and I didn't see the story though!
So, the idea is perhaps a synthetic corruption kind of story? Like... could be an angry robotics factory taking people and making them into robotic servants to get more. Or there could be a nanomachine 'plague' or someone using nanomachines to improve people in their eyes. If you've heard of the Dust from the game series Endless Space/Legend/Dungeon of the Endless, then that's the best analogue I can make

Thanks for the idea; I never though about this before and it is going to be fun to explore it ^^