crazy prediction
generations are not going to last longer than they did in the past. The reason the PS2 managed to sell well for like a decade was because when it first arrived on the scene (that whole generation with Gamecube/Xbox) it was SUCH an improvement over the prior generation in terms of technology and visuals. Also the fact that it was coupled with a DVD player
constant micro improvements to computer gaming, which already has a large lead to consoles, will just further push console manufactuers to having shorter generational period
the problem with consoles currently is that they can't easily be improved or replaced in terms of parts. what you have at the start is what you have at the end in terms of hardware.
which is a big reason why I think in the next 10 years you will see a giant leap to home computers and consoles merging. at this point computers have a massive advantage in terms of being able to replace parts as new games and technology arrives, and that will only grow
I mean realistically in 5 years a mid tier computer will be capable of playing games visually at such a higher level than the PS4 that it won't even be funny. as it stands mid tier computers can play games much better to begin with! just realistically you can't expect consumers to consistently purchase this system that far down the road
a 10 year life cycle is unrealistic. obviously expect the PS4 to pass 100 million in the next 2 or 3 years but its peak year is probably 2016 and undoubtedly another big console (besides the NX) will be released either prior to 2020 or right around then. mark my words. its just inevitable due to computer pressure and the possibilities that exist from decent PC's. people obviously will always still buy older systems but at the rate things could change in the next 5 years its unrealistic to expect it in the numbers you're predicting
things like the PS2 and the DS are exceptions and I would argue that the current PS4 dominance is partially DUE to Microsoft and Nintendo dropping the ball a bit. for all we know the NX could be a giant hit like the Wii and something like that alone would absolutely kill the momentum of the PS4 coming close to the milestone you suggest. too many variables that point to it not happening
if you had 5 more guranteed 2015 years then, yes, it would seem possible- but there is no example of a generation in which a system could maintain that sort of level of sales for so long. unless you doubt that 2016 is likely the peak year for the PS4 (it probably is though regardless of what you think)