I always wondered why not much effort has gone into improving speeds over copper and if it was because we simply maxed out the physical capability of it. DSL typically maxes out at around 12Mbps and you have to have a very good phone line with extremely low capacitance. Like practically within a couple km from the CO. Wonder how this service will be different and capable of breaking the barrier. DSL is also designed to allow voice through at same time though, as it uses a different frequency, so if you don't care about voice I imagine you can use a bigger spectrum.
I forget what kind of speeds you can get over a Conklin. Those are basically DSL but at like 360 volts. They are used to extend copper for long distances.