WiMAX is extremely common in Japan, with tens of millions of subscribers, though I'm not aware of anyone who uses it with native drivers. It's all WiMAX to WiFi/USB pocket routers and the like, regardless of how you connect to them Linux will just see some flavor of a cooked Ethernet interface.

It would be interesting if anyone is actually using this at the lower layer with these drivers though. I've never heard of it. It seems like a closed ecosystem where the ISPs always provide the equipment.