Well, it is coming to Canada. We have a 4K Sports Channel starting in January. It will have NHL and MLB games. Yes, it is small but it is a start. Rogers also has a Netflix style channel starting with 4K content. If Canada can ramp up production that quickly America certainly can begin to as well.
I have Gigabit fibre and it be available by year's end from the other major provider in my city. Gigabit fibre is being announced and rolled out quickly in Canada. Again, phone and cable companies in the US can start this as quickly as it is here.
Fox has announced major studio releases in 4K will be available to purchase as a download. You also get a blu-Ray disc. Great way to use my fibre
So, chips are available to process 4K, content is available with more coming, iPhones have 4K recording and iMovie can produce 4K movies. Apple should be a leader and have installed 4K in this box.
Do I have a 4K TV? No. I am waiting to see what the HDR requirements are for the Sports channel and then I will buy. I will purchase a new receiver once DTS:X is released. I'll buy a new AppleTV when Apple updates the box to support 4K. I just wish it was now.