What makes you so sure of this?
1. MS couldn't win a generation sales-wise despite an absurd amount of dedication, luck, and Sony screw ups (Undercutting PS3, year headstart, Bluray/Cell BE, Kinect revitalizing sales, etc)
2. MS is exiting the console business as we know it. They no longer believe in generations and are seemingly turning Xbox into a PC subdivision of sorts.
3. Where are the Xbox exclusives?
4. MS' s first parties reputation is rapidly falling. Sony has 5, and soon 6, IPs that are bigger than MS' biggest, 343 Industries Halo, a series that is suffering a Spyro/Crash-esque decline.
5. VR, which Sony is the current leader of, is the future of games with a first person perspective. No, it isnt another glorified Eye Toy.
6. PS4's lead over competitors is oddly similar to PS1's.
7. Xbox isn't nearly as important to Microsoft as Plastation is to Sony.
If u think the sum of the above amounts to nothing, then I really don't know what else to tell you!