Wireless would help, but not very much. You can get a whole lot more bandwidth through a fiber network than you can through air, because you can double your bandwidth by laying another fiber next to the first - or put in 20 more fibers, or a thousand. Those don't interfere with each other, whereas free space radiators do.
Wireless could help with the literal last mile. The cost of deploying broadband becomes exponentially higher as you near the edge due to the sheer number of links.
Hundreds of megabits with one mile range is easy now and is faster than many cable plans. Gigabit is on the horizon and probably achievable within 5-10 years, especially with enough spectrum. The problem is that current available bands are a poor choice for this. Some bands dedicated to last mile ISP service that have better range and less interference would really help.
