I can see problems with this. First of all, if this is a product generally available to consumers, then with massively increased distance comes the problem of massively compounded saturation. We already have this problem with the current generation of Wifi. In a dense neighborhood, you cannot find any clear channels, and since adjacent channels interfere with one another, transmission speed can degrade extensively.

Now imagine if a WiFi signal could easily travel several miles. Yes, in the TV whitespace you have much more bandwidth available, but you simultaneously have many more base-stations sharing the same channel. The better the range, the worse the potential for extensive interference, and a degradation in transmission speed.