Interesting. The author suggests that open spectrum at 5 GHz can be made much more useful by using MIMO (multiple-input, multiple-output) signal processing and beamforming rather than omnidirectional transmission.
It's been known for some time that "smart antennas" could massively improve performance of transmitter/receiver stations. Indeed, back several years ago, the FCC modified the rules for unlicensed devices to take this into account. As the author is plugged into the industry, I'm not sure if this suggests a wave of new devices or simply a reaction to the current "spectrum crisis" talk and the focus on opening new spectrum for CMRS (what normal people know as cell phone service).
Wireless policy in the US has a huge blind spot in that it is very heavily CMRS focused. Well, with something like 200 million devices in use in a multibillion dollar industry, that's understandable. But a lot of growing applications, especially machine to machine (M2M), get shafted as a result. Not sure if the improvements in MIMO and beamforming have significant policy implications yet, but need to flag for further monitoring.