I can see it if a couple of things happen :
(1)- Microsoft decides against continuing the attempts at home console operations, and transitions to a true mobile-first/streaming/PC philosophy. This is actually fairly likely considering the bad profits they've seen from trying things as they are now. They more than anyone know that the money is in the software/games rather than in hardware. It's weird to say, but Microsoft would have made 50x+ the money in gaming had 'Xbox' simply been a gaming studios ensemble for all platforms instead of an attempt to take over the living room to ward off threats that never materialized. Everything that Microsoft feared Sony would accomplish has actually taken form in devices/platforms from Apple and Google. This can't possibly be stated enough.
So under this possibility, X1 is nominally supported for another 3-4 years and begins to fade out (think Wii from 2012+).
(2)- Pricing gets really good. $299 is probable for 2015, but from there I think hitting $249 and eventually $199 could REALLY give PS4 some legs.
I think the low end will be 110M Lifetime, high end 150+.







