How would Mantle matter for that? It isn't used in either of the consoles and it has to add time, not reduce it for PC since DX is mandatory.
The investments for games is made for the consoles.
Now ms and sony is similar and similar to mantle. That means if you code your engine for consoles with very little work and very little investment you have it for mantle pc. With good quality ports and good speed at the same time. That is a huge change. And its important to stay compettitive with the other content providers. Mantle covers the low level hardware where the coding is most expensive. But also where the gains is the be had. There will be classes of dx on top of it but as ryan said; the api.
Will that mean less coding for dx and other players and eg. Nv or Intel gfx? Ask EA. I think they will use a larger part of their investments other places.
Mantle is a big and growing market on pc because its not only 7 series+ gfx but all jaguar and future apu onwards is mantle. The new ones with true sound most similar as they have similar dsp.
But as i wrote probably all the soc similarity is there in the future perhaps even including hardware security part.
All is speculation. But it looks like EA is betting on Dice and frostbite. And dice is using mantle as a platform on the pc side because its the same as the consoles.
Yes mantle is for pc. But its the same hardware to the consoles. And amd have confirmed coding is similar if not directly compatible. Its all the same. Mantle is just a name.
Put in other words than how ryan wrote it:
Mantle is the platform for pc, xbox and playstation
Similar api, similar hardware