Male cages have gone from being an extremely niche thing to something that can be bought in at least some high street sex shops, and the designs have improved hugely. There are new cage designs showing up from the Chinese producers every few months at this point. Manufacturing quality and flexibility for plastic products continues to improve quickly. and it wouldn't hugely surprise me if, a decade from now, practical plastic female belts reached a similar price point. They wouldn't be inescapable, of course, but they could be tamper-evident.
The growth in male cages hasn't lead to huge societal changes, although from the sales figures, I suspect they are getting more casual use than previously (heck, I even saw a chastity cage / pokemon meme being circulated between what I assumed were relatively "normal" students). I doubt there will be much of an impact if belts go the same way.
