But in a way he did answer your question. 3G is a label for cellular packet data. There is no simply need at all for a "3G hotspot"; anywhere you have cellular data you would have 3G coverage (provided your carrier offered such a service). In effect, the whole country is a hotspot.

802.11n is the next revision up from 802.11g, so yes, N will replace G in time just as G replaced 802.11b. The key is interoperability (i.e. why 802.11a failed to gain much traction at all as it was not interoperable with other standards as it operated at 5.8 Ghz instead of 2.4 Ghz). It's hardly a new thing. Old modem technologies always eventually superseded previous standards, and it took years for 802.11g to supplant 802.11b (I was running a B network back in ... 1999?).

WiMAX will see only limited support at the integrated hardware level as it is reliant on a carrier/provider/ISP of some sort to give you WiMAX service. I would never buy a laptop that required me to sign up with Company XYZ's WiMAX service to utilize hardware someone felt like shoving in my laptop. It has it's uses in devices like the OQO, but you don't see those flying off store shelves. Demand isn't there for such an expensive, locked in product. I don't even know if I'd want WiMAX as my at home internet service.

The need for a USB interface to connect to an adapter to connect to another service is a bit redundant. If you already carry a 3G cell phone, both devices are already fully equipped and capable of connecting over Bluetooth. Yes, eventually Bluetooth will become the bottleneck (if it isn't already) and we'll crave something faster, but by then these devices will have evolved well past their current iteration and likely have all of those things you want.