Supposedly the average on ATT/VZ DSL is around 20-25GB per month but that number is trending up obviously and has a lot of people who haven't found services like Netflix. Those people will find Netflix when they finally buy their next TV or DVD player.
I'm not saying that this can't be a threat to unlicensed WISPs, but as it stands now it is not a serious threat for all the reasons mentioned already. When I do a mobile speed test on VZ LTE I get 30Mbps down and 15Mbps up. Impressive, yes, but I'm can't test more than once per month for fear of using up my usage allotment.
What you see here instead are indications that AT&T wants to give up uverse and landlines and focus on mobile wireless services. IMO that creates an even greater opportunity for WISPs. There will be a rather large gap between mobile, tightly capped service and home services that need larger caps. WISPs are already filling that need and have proven that it works - we just need to keep moving ahead with innovative technology and business models.
-Hal