Is not true that mantle is harder to develop than direct X. I read an article about mantle and is going to replace direct x. Also developer laziness isn't a excuse.
AMD's Mantle API will not be replacing DirectX in any future PC versions of video games at all. Microsoft is infact working on further developing and optimizing DirectX 11.2 to match AMD's Mantle API or even beat it. There are rumors Nvidia pushed Microsoft for this.
Nvidia is also going to further optimize and support OpenGL to match or beat AMD's Mantle API. Intel, Nvidia, and a few others do not care to support AMD's Mantle API on their hardware. Strange thing is AMD's Mantle API works on Intel hardware though.
The PC version of Battlefield 4 and the PC version of the Frostbite 3 engine still supports DirectX 11 even though it also supports AMD's Mantle API.
Yesterday I belie it was I read from Johan Andersson he said only like 35% of the PC gamers who play the PC version have AMD graphic cards and tried to play the PC version of Battlefield 4 on AMD's Mantle API.
Windows keeps growing and the use of DirectX keeps growing I guess people just stick with Windows and DirectX because Microsoft offers better support and like Guy N'wah said their is no point to support something that there is a really small market from and has no return on investment yet.
Doing stuff like this can make your company go bankrupt. I should know I buy and sell stocks and the things I see people complain about in the chat where I buy and sell stocks is quite sad in some cases.
You want CD Projekt RED to keep existing as a video game company and to keep gog.com alive right? Because they are like the only video game company in this video game industry who are pushing for 100% Digital Rights Management (DRM) free future to exist side by side with Steam and to develop some of the best RPG video games out there that don't exist other than Bethesda Game Studios ones which are starting to suck and bore me.