Please it's like a best of both worlds between 7 and 8 :-P
8 was a good OS, people just freaked out about the start menu going away and couldn't handle change! "Oh noooooooeeeeesss it's different! Make it go away!!" Cry babies...
7 is old, and Windows 10 resembles 7 more than 8. But things like the Metro UI (which Microsoft doesn't want you to call it that anymore) are brought into the start menu.
You know what else worked? Directx9... and 10... and 11... why bother making new ones? The old ones worked just fine!
the main reason to upgrade really is exactly what you said. but when the vulkan api is pushed and developed, will probably go full linux.
There would need to be some pretty significant changes in the PC market for Linux to EVER become a real player in PC gaming.
Linux holds such a pathetically small market share compared to Microsoft, that no developer is going to waste the time to make games that very few people are going to play.
Vulkan will require a graphics driver that supports the API, and on that specific OS. Good luck getting that from Nvidia. AMD might make a driver with Linux support, but it will have all kinds of problems...
Once it becomes PC friendly, and appears to run faster than Windows and Mac, it will be more popular :P
The problem is, no one is making money off of these operating system, so no one is going to advertise them and you will likely never see them on Store shelves. Just not enough exposure.
What about for Windows?
What about for Apple?
See the problem?