4k won't be mainstreamed for nearly a decade.. primarily because of the dysfunctional deployment of bandwidth around the country (by catv providers and telcos) is also dismal. like it or not, there is a growing demand for access to video programming via the internet, so until that is developed more.. video will stall in it's evolution. BTW, consumers are STILL waiting for affordable 10 GIgabit (ETHERNET) routers/adapter cards which don't cost an arm and a leg in the residential consumer market. The power requirements will likely be higher for 4K./UHDTV with near 20 gigabit hdmi similar to what you have today in 10-40 gigabit Ethernet controllers. Early adopters always get screwed.. look at display port.. it had a good run, but it's not been adopted by major HDTV mfg as a standard-- therefore, HDMI FTW.
I like HDMI, but more likely wireless HD streaming via 802.11AC and its successor will be what most people use in Smart HDTVs. Even after 8-10 years, you will STILL likely find COAX and analog RCA cables as connectors for those with analog VCRs still working in 2020-2025.
I can just see somebody using an old TUBE tv watching Back To the Future on a VCR... LOL!