Meh, don't see the point. You're only saving 3cm in each dimension and yet there are massive trade-offs, notably no PCI-E slot at all and SO-DIMMs. Plus I don't see what this would be used for that can't already be done (and better) with Mini ITX.
AMD APUs have more graphical grunt than Intel 6th Gen and a lot cheaper too for HTPC use. Also, APUs are plenty powerful for browsing and office work if you want to go down that route. OK, Intel chips usually have better virtualisation stuff if you want thin clients, but again Thin ITX has that covered too.
Mini ITX is plenty small enough and if you want a build this tiny you can still use a Pico PSU and power brick.
Personally, I'd much prefer to see a revisit of Mini DTX - give us 2 PCI-E slots on our SFF boards people so we can drop a dedicated sound card or PCI-E drive next to our GPU or even SLI/Crossfire with single-slot cards!