It's very niche
High Altitude platforms (which as yet are not viable). Satellite mesh networking among satellites.
Actual terrestrial range is pure line of sight and very limited by weather.
Infra red laser is nearly more useful. It's a lab party trick, because they can.
The "spectrum" shortage is a myth. The whole point of Cellular is to re-use the same nine channels (minimum is three, but nine is better if a mast only uses 3, one each per 120 degrees). The problem is two fold:
1) Stupidly having more than one wholesale operator. If you have four, then you need x4 spectrum.
2) Not enough basestations. Because of ROI, it's not economic to have smaller cells and give people x10 speed as they won't pay much more.
The real impetus of selling off TV spectrum, Army & satellite spectrum to mobile is:
1) Extra licence revenue to Regulators and thus Government.
2) Cheap low capacity for rural without building new masts, use the GSM ones,
3) Cheap extra capacity in cities, to compete with WiFi points, without extra masts. This is why they want LTE on WiFi, use existing band, tech and charge you more.