As more and more people move from cable and satellite TV to IPTV/internet streaming, those products are in great demand and that demand is growing. The thing is, the profit margins on them are so small, Intel would rather use their fabs to build Core I# and Xeon processors that they can sell for a hefty mark up. NUCs basically get the left overs (older fabs) because Intel really doesn't care. The fact of the matter is that market will never have huge profit margins--it's always destined to be a volume seller. This is the same reason why Intel doesn't care about smartphones.
Consoles (they are custom SOCs so addressing both here...) are in the same boat as NUCs, tablets, and smartphones: volume products with tight profit margins. AMD may dominate the console market but NVIDIA dominates the desktop market. Games are developed on Windows which overwhelmingly run on NVIDIA hardware. Developers may be quite familiar with the ins and outs of GCN because of optimization for consoles but they're optimized on NVIDIA first because that's what they're coding on.
AMD is open-sourcing virtually all of its APIs. That's great for Linux but that isn't going to translate to profits for AMD. Well it could because AMD is more appealing now on Linux but realize we're talking about a minority of minority of systems here.
It's a DirectX 12 thing. Some things, especially textures, don't require 32-bits of precision. At 16-bit, it should be able to process two calculations for the price of one.
Developers aren't using 16-bit because hardware support is iffy. Five years from now, 16-bits to handle textures will likely become common place.