said by quetwo:
With modern cable systems, this is no longer the case. This is all just a matter of bandwidth. 4k signal takes 1 QAM with minimal compression running at MPEG-4. 8k signal will take 2-3 QAM channels each @ 6Mhz. (You can get about 3 - 5 720p channels into a single QAM, and about 2 1080p in a single QAM with minimal compression).
Modern 1Ghz systems (which, not all systems are at -- many are currently at 800Mhz or 550Mhz) can have ~ 157 QAM channels, although you wouldn't usually wouldn't have that many.
When you account for technologies like SDV (which is already out), you gain even more bandwidth in the final mile. There will be even newer technologies that come out soon that will allow even more bandwidth in the final mile by the time this hits the main-stream.
I know all of that...
It just gets to a point where fiber is cheaper. Especially when you can mux 20 or more wavelengths on a fiber and each wavelength has as much bandwidth as a 1Ghz or more cable system.
Everything is going to IP anyway... cable is pushing IP all the way to the hub at the edge of their network, then converting to RF just to get over the last mile.--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.