> You can have multiple competitors in one space with comparatively limited infrastructure investment on their part.
Spectrum and tower licensing is off the hook, and it's unlikely that more than a handful of companies will have the business acumen, capital, and regulatory skill to build up a network of significance. Any 'gigabit wireless' scheme will likely look the same it does today: a handful of key players with reciprocal data roaming agreements, and a few MVNOs which piggyback off the big guys. Wireless infrastructure is so expensive that carriers don't even have full coverage: they share. You're not always on 'Verizon's network,' sometimes you're on Sprint's network shared to Verizon. For CDMA, these are sent to the phone via PRL lists[1].
The MVNO scheme happens in DSL where it is called a CLEC[2], where the local telco is required by law[3] to allow other companies to lease its lines. This is how companies like Sonic.net exist. If I understand correctly, the same forced-lease agreement is not in place with cable, which is why people are talking about a 'cable monopoly' here. There is no such thing as Sonic.net for cable, and DSL is physically limited to about 20down/1up. Thus, there is no competitive high-bandwidth pipe to the home until fiber comes into play. Note that DOCSIS3 can easily push 300Mbps down 100Mbps up[4]. You already have this capability if you have cable, it's simply not turned on. If you were a cable company, why would you?
"In the UK, broadband provider Virgin Media announced on 20 April 2011 an intention to start trials with download speeds of 1.5 Gbit/s and upload of 150 Mbit/s based on DOCSIS3.0.[4]" <---- this is with literally the same kind of coax and modem in your home right now.
[1] http://en.wikipedia.org/wiki/Preferred_Roaming_List
[2] http://en.wikipedia.org/wiki/Competitive_local_exchange_carr...
[3] http://en.wikipedia.org/wiki/Telecommunications_Act_of_1996
[4] http://en.wikipedia.org/wiki/DOCSIS