While (I think we'd all agree that) predicting technology decades ahead is hard,
it is not impossible that a group of specialists, after a thorough discussion, could
get the prediction about right.
I linked you to the report of Bell Labs achieving 10Gbps over copper wire. Here is the link to them achieving 100 petabits per second over fiber in 2009:
http://www.alcatel-lucent.com/press/2009/001797 This transmission experiment involved sending the equivalent of 400 DVDs per second over 7,000 kilometers, roughly the distance between Paris and Chicago.
These are demonstrated capacities for these two mediums. The only limiting factors for achieving such rates for individual consumers are physical and economic considerations for building out the infrastructure. Nonetheless the technologies for achieving exponential increase in bandwidth over current offerings is proven. Achieving these rates in practice on a scale coinciding with historical exponential growth of 50% annually, which
does take into consideration economic and physical realities, seems well within reason. I'm sure telecommunications specialists would agree.
As a telecommunication specialist, No. I do not agree.
Sure, we were also able to get x.25 and x.75 telecom to run over barbed wire, in the lab. (There are places in the world that still use these protocols, some of which would deeply benefit from bitcoin in their area.)
The logistical challenges of implementation is not what you find in the lab.
This stuff has to go out in environments where someone backs up their truck into a cross country line so they can cut it and drive off with a few miles of copper to sell as scrap. We live in the world, not in the lab.
Designing something to work and designing to not fail are entirely different endeavors and someone qualified for one is not necessarily qualified to even evaluate the other.