HDMI hasn't helped this issue either. We've had DisplayPort for PCs for years with way more bandwidth than what's possible with HDMI.
I suspect HDCP does not help either. The protection this provides is easily bypassed for those who it's supposed to hinder, but instead it prohibits practical usage. This was a huge headache for me. All I want to do is play music from my pc while playing console games without loosing game audio (both connected to a Denon 4520CI), but I have to choose between loosing surround sound, exclusively one or the other, or unacceptable audio quality loss and latency.
Video cards are much better at doing this kind of processing than a CPU. This is why nearly all deep learning is done with Nvidia chips and very new intel chips (I know nothing about ATi/AMD but they've been well known for bitcoin mining lol).
However, the biggest issue right now is performance. There is no way all of this can be done with low latency (16ms or less), which greatly restricts the use to view-only applications (read: not suitable for computer use and especially not gaming friendly).
And let's say HDCP was not an issue or whatever and we can process everything via computer. This will require massive bandwidth, and not even the new Pascal Titan Xp only has 11.4 Gbps GDDR5X memory, so there would have to be compression (latency) or lower quality (4K resolution now moot). Don't forget more resources being reserved for OS usage (even with DX12 instructions bypassing the OS).
I'm still waiting for a device that meets all of these points (low latency, 4k, 4:4:4@60Hz or more, 3D support) and without costing more than my own display (LG OLED E6). Terrible CMS controls, but I still think the true blacks are better than glowing blacks