You've still got attenuation in the wires.
You've still got FCC / CE emission requirements to meet.
You've still got the effect of connectors.
OK, so they've done 1Gbit/sec over copper (Gigabet Ethernet, which is short range), so I wouldn't be surprised if with improved technology they could do 10Gbit/sec -- but not at the ranges required for cable.
If it works out for cable, great. I won't count on it.
Tony