Epic read – and makes me wonder how long fixed services can truly survive. These kinds of speeds with little infrastructure surely scale better for those making the money, and are easier to implement for consumers too.
Spectrum is finite though. You can add more fixed clients by adding more hardware at the CO and running more fibre. Eventually, even if no one is even actively downloading, your cellular network will saturate just from the number of clients. The same is true of wireless networks today. An 802.11n wifi network is also limited by the number of clients, even if none of them are consuming their share of bandwidth.
If you aim well enough, that finite spectrum is only shared by a handful of clients.