The sensor is much more than 4K. I think it is the internal processing that is holding it up. To save out 4K lossless at 60 frames takes a lot of horsepower. Anyway, DLSRs have never been all that great at video. Canon does sell some excellent high end video cameras that also take mediocre stills.
How do you get your Internet? I have only one choice for broadband, cable, and it is expensive, often goes down or is slow and I'm convinced they throttle it intentionally when I try to stream a movie. (TWC)
It apparently works for him, however, personally, I don't use my iPad to that extent because I have an iMac 5K and a Mac Pro and a MBP so iPad is just a casual device for me and I am sure many others fall into the same usage scenario.