[Allanbuzzy]

Short answer: Broadcast capacity can't fit loads of HD channels and would require upgrades to the pre-existing satellites/cable/terrestrial systems. Unless they make internet feeds of their channels, it ain't happening.

Long answer: It would require entire upgrades to their infrastructure, be even more costly to run and probably be a waste of space if it's something like 4Music or MTV Music. I mean, you can watch music videos for free and in 4K through YouTube or XITE/Vevo on Sky Q. For channels like E4 Extra, would the benefit really be there for a repeats channel? I guess you could argue Talking Pictures TV could be a much better channel in quality with the upgrade but a lot of those old films are low quality anyway so what difference will that make?

Personally, with the advent of internet-based television, I do think there will be more default HD channels cropping up (given that the BBC are pushing to give viewers at least some way to watch HD feeds of their channels through iPlayer on Freeview despite COM7's closure and bandwidth taken by their local channels). Hell, I'm sure Paramount are just as close as to just putting their music feeds instead onto Pluto TV, running automated and in better quality. Having, for instance, the whole of Freeview being streamed and in 720/1080p default on phones and tablets would be the dream. Of course, it isn't gonna happen.