If his math is correct then 8k, which is 4x the pixels of 4k, would need 4x that bandwidth, and even Intel's Thunderbolt 2.0 is "barely" at 20 gibabit/s, which means we can't go much further yet. It will be a while until we reach 80 gigabit/s.
8k is also an OUTRAGEOUS amount of pixels to throw around. Unless you're eyeball to eyeball with a 40" display, your eye can't distinguish between 4k and 8k.
We all know 4K is next, we know that clearly there'll be something afterwards, it would be good if the next hardware we buy planned for that.
Thunderbolt, BTW, has similar limits: http://superuser.com/questions/441395/what-is-the-maximum-re...