To add to the bandwidth requirements we going to cater for the 120 Hz Ultra-HD people. That's around 24 Gbit/sec @ 8 bits per pixel. So the high bandwidth interface are here to stay. Cheaper to keep the tooling (HDMI-contacts) and raise the standard to 2.1 than using CAT8 cables.... or USB4.End of the day we still need interfaces for uncompressed video, simply because encoding video + sending it over a low-bandwidth interface + decoding a video adds latency. 30ms of input (e.g. mouse) to video latency can make your life miserable.
I just wish we could replace the HDMI with the DP, it's slowly coming to the higher end TVs. But our devices (consoles, AVR...) wont change.