If you just want to say "phone line" without specifying UVerse, Bell Canada is doing 50/10 on a regular phone line (VDSL2 with FTTN), and line-level bonding should be able to break the 100 Mbps mark over a single 4-wire phone connection. 4K broadcast video with h.265 should require at least 20 Mbps or so to match the current perceptual quality of ATSC broadcasts on a pixel-for-pixel level.
In short, 4K video over telephone lines should really not be a problem, at least for users very close to the DSLAM.
I'm on 25 meg VDSL2 right now, and my line stats show an attainable speed of 62 megs, and Bell is selling the 50 meg tier today, so this isn't some pie-in-the-sky future thing.--
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