While I believe this technology has potential for local networks from a large factory to a small village, I don't think it's a proper substitute for optic fibre over long distances or even service within towns and cities.
Being an RF system, there are a number of limitations:
1. Frequency. If it's in between TV channels it will be either VHF or UHF, in other words with radio propagation characteristics similar to TV. In hilly areas it might not propagate well and result in 'dead spots'.
2. Bandwidth. Basically the wider the bandwidth the faster the speeds you can transfer.
Wider bandwidth means greater scope for interference with your neighbour's system.
It also means less transmitting range since the signal is dispersed over a wider range of frequencies, compared to a narrow/low bandwidth signal, such as an AM radio transmission.
You can overcome this by having lots of repeater stations (expensive in the country) or by using very high transmit powers and antenna masts. For instance capital city TV stations might use something like 100 kW of transmitting power to send a signal with a 7 MHz bandwidth. I would imagine real broadband data might involve much higher bandwidths than that, making the problem worse.
3. Need for two-way broadband. A crude form of broadband is where you can receive information at high speeds but can only send at low to moderate speeds back.
This is fine for most domestic users, but commercial and industrial users with advanced needs will want high speed in both directions.
As mentioned above, in a radio frequency system, high speed requires high bandwidth and high transmit power. The power consumption is considerable, especially for advanced 'always on' systems with high speed in both directions.
You can avoid high power by having lots of base stations, such as with the mobile phone network. But this has limited coverage in country areas.
I do see RF as having potential at the smaller scale very local level. For a farmer wanting a telemetry system to monitor dam levels and send the data to the homestead a wireless system is ideal.
A more advanced system (several times better than wifi) might serve a very small town with a dense population. Maybe a mining town with few people living outside it. But as soon as you have populations around the town rather than just in the town, just like with a cable-based solution the costs of providing adequate service rise, especially if you want high speed both ways.
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