To my knowledge there is no current plan for Quick Sync on Xeon except for the bottom-end E3 (which Mac Pro does not use). It is already present on Xeon E3.
Quick Sync will be further enhanced on Skylake "Core series" CPUs (i3, i5, i7). This will apparently include JPEG, JMPEG, MPEG2, VC1, WMV9, AVC, H264, VP8 and HEVC/H265 video and image formats. The Skylake CPUs are scheduled to ship later this year.
It is obviously frustrating that Xeon E5 and above still doesn't support Quick Sync, especially as it is being further upgraded. This is because Quick Sync is tied to the on-chip GPU, and Intel apparently judged the required transistor budget too costly to include in the mostly server-based E5/E7.
While Quick Sync uses on-chip GPU resources, it is not a GPU task per se. It is essentially an on-chip transcoder ASIC. For this reason a discrete GPU (no matter how fast) cannot compete with Quick Sync for encoding. Interframe encoding is an inherently serial process which requires frame 1 to be processed as input to frame 2. The central algorithm cannot be parallelized so isn't amenable to acceleration by GPU or AVX. The GPU and AVX can assist to a limited degree by marshalling the data for the CPU to handle, but that's all.