MS just killed mantle with that news of DX11 cards are compatible with it. DX12 doesn't have to be as close to metal as mantle is and it would done it, since it has to be made to work with diff card markers has to have be able to deal with some issues. As for AMD not adding support for old 5k/6k cards not real shock as talking like 3 year old cards now. If mid to late 2015 is time table for it then cards will be just that much older, But AMD probably won't get as much flak over the matter that Nvidia would if they did same thing. Nvidia supports all DX11 parts where as AMD is gonna leave out 5000/6000 series cards. only 7000 seires and up will support it.