Games will also continue to become more complicated leading to better connections being required regardless and companies will also continue to abuse data caps. Streaming video games has a place no doubt (rental) but its simply not practical everywhere.
Netflix isn't practical everywhere either. Hell it doesn't even most new release movies.
Yet Blockbuster Video is extinct now and so is basically all movie rental houses, and that used to be a staple of America at least, going off to Blockbuster with the family on a Friday night to pick out some movies.
Things change. Fact of the matter is too, the people who grew up on things like the PS2 (or even earlier) will be like 40-50 years old in 15-20 years. That encompasses most of this board. Their opinions on hardware media are simply not going to matter as much.
This board insists over and over again that no one should play smartphone games and you need real buttons to play "real" games ... but you ask a kid who's 9 years old and he doesn't give a a shit about any of that he didn't grow up with a NES or Playstation that stuff doesn't mean the same thing to him.
Once you have things like Google Fiber or its alternatives spread throughout most of North America/Europe/Japan, it doesn't matter what the graphics capability of a game is because the signal is just being streamed, but the control lag will be reduced to the point where most people simply won't care for physical game consoles IMO.
That and on the other side you'll have smartphones that are absurdly powerful in 15-20 years capable of generating basically any type of game world at a high quality and being able to display that graphic on any display with the snap of a finger. You'll just need a controller if even that.