I can only imagine the outcry that will occur when Facebook blocks right click, save image.
Actually, I think that would be a business opportunity for a startup, only I can't figure out the tech you'd need to do it. There are shops (like, for wedding dresses) that disallow you from taking pictures of their stuff because you might share it online; they'd make good customers.
If the image can be shown, it can be copied and sent to anyone.
Even the recent article about switching two images very quickly can not solve this issue.