Paul Boutin muses in a Slate column about the future debate between commercial wireless networks and municipal networks: He concludes that ultimately cities and corporations will use WiMax but the end results will be different. The corporate networks will run over licensed frequencies. They'll be more reliable and will cost more for end users than city-run networks. The public networks might be free to use but won't have as great coverage as the kind you'd pay for.
That's a quite possible scenario. However, I wonder if some municipalities will end up getting burned by Wi-Fi and decide not to do WiMax. Depending on the gear they use, it may not make sense for municipalities to build citywide Wi-Fi networks, as Boutin points out, because of how difficult it is to blanket a city in Wi-Fi. Maybe some cities will try, largely fail, then be reluctant to try WiMax because of the experience. Enough companies may build WiMax networks--using licensed or unlicensed frequencies--that perhaps municipalities won't decide to build their own (although that hasn't stopped cities from building Wi-Fi networks). That would still leave the door open to community networkers to build their own free-to-access WiMax networks, if the price of gear drops low enough.
Boutin suggests that cities would do well to try to make deals with the owners of prime WiMax spectrum so local volunteers can build quality networks in underserved areas. However, I find it unlikely that the spectrum owners would do that. The underserved areas are exactly the market that they can best target with the spectrum. The big telcos that own this spectrum haven't been willing to bring lines to underserved, sparsely populated areas because it doesn't pay off. But with wireless, the network is far cheaper to build and could more easily spell profits.