A gift or a bludgeon?
The biggest question about DirectX 12 has nothing to do with its technical details, however--it's whether Microsoft will make the API available on existing operating systems.
Microsoft locked the most recent point upgrades for DirectX 11 to Windows 8 machines alone in a bid to spur adoption, and restricting DirectX 12 to Windows 10 would give PC gamers grumpy about Windows 8 a clear and compelling reason to upgrade. Microsoft hasn't said one way or the other, but I'd be shocked if it didn't make DirectX 12 a Windows 10 exclusive. I hope I'm proved wrong though.
DirectX 12 isn't currently in the Windows 10 Technical Preview, but developers (and only developers) can sign up for the DirectX 12 Early Access program for an early look at the API--and yes, the provided bits will work with the Tech Preview.
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