really Linux Ubuntu / Linux Fedora would have beaten Mircosoft into the ground if almost everything also supported it but as almost everything supports Windows first then ports to Mac and/or Linux Ubuntu and/or Linux Fedora Windows has the big lead. On paper Linux beats Windows in specs, in useableity, in general use, and in server side programming but to the general consumer as most if not all the computers in the retail store are going to be windows 8.1 atm and the time of March 2015 it will be windows 10 everything is windows based especially games as most games run better with DirectX than on OpenGL and Mattle really will require the programmer to make their own shaders from the ground up instead of useing API calls to make custom shaders to this when the programmers make custom shaders it costs more and puts a bigger risk into the game as it is a " non-standard shader " so security patches for it will have to come directly from the programmer(s) who made it and that is even more overhead onto them.
DirectX12 will most likely be used in games soon after Windows 10 is out becuase of UE4 natively supporting it and the preformance increases it says will be there but at the same time a DirectX 9 and DirectX 11 version will most likely be in the same package alike to the Civilization 5 game where it allows you to choose between DirectX 9 and DirectX 11 in which the software detects if you can do DirectX 11 so you do not crash.
to the guy above who said "OpenGL and Mattle will stump out DirectX" while OpenGL has been around for almost 20 years and DirectX is still going strong with both OpenGL and DirectX support on every video card on the market which i can see ... maybe not Tesla and AMD compute cards ( if AMD has a compute card ) but all the others do have it and DirectX is running supreme so far but also does OpenGL have a market for the indie devs, Linux makers, and open source programmers while DirectX explicitly says it can NOT be an open source program when using DirectX.
Windows 10 and DirectX 12 will take the new computer buyers by storm but that is only becuase they do not want a mac or even know that their stuff can run on a mac and/or on Linux while using WINE.