Also DirectX 11 was originally supposed to be the last major DirectX version with only some minor updates planned, since Microsoft saw no additional parts of the graphics pipeline that could additionally accelerated by hardware (Source: some AMD talk a few years ago).
A few months ago DirectX 12 was announced (and it's quite probable that AMD's Mantle was the reason for this roadmap change).
A few months ago DirectX 12 was announced (and it's quite probable that AMD's Mantle was the reason for this roadmap change).