There's only one system this generation cycle I see that has a shot at 100 million, and that's a Sony system (yet again). And no, not the Vita, *snicker*.
Smartphones/tablets have just changed the entertainment paradigm too much, even in 4-5 years I think it's going to be a problem for even traditional consoles because you'll have phones/tablets that can generate graphics on par with maybe a PS4, and that will be "good enough" graphics for a lot of people. All you'll need is a bluetooth controller.
In fact the Switch might inadvertently actually cause this process to accelerate because if Switch has a little bit of success, you can bet Samsung and other companies will start releasing tablets/phones with cheaper "Joy Con" like attachment controllers.
Right now they are available but they're not really pushed by the big hardware manufactures and they're big/bulky and way overpriced. Someone starts selling a Joy-Con type controller for Samsung tablets/phones for like $30 which is well designed and developers start supporting it ....







