The "day of reckoning" has little to do with wi-fi or wimax. The "day of reckoning" has to do with streaming from cellular towers. Wi-fi, in particular, is a short-range technology that extends a wired connection - typically with plenty of bandwidth - to a relative handful of users within line-of-sight. Wimax covers a greater distance, with more potential consumers, and isn't likely to be used in densely populated areas.
The issue for cellular is that there's a limit to the number of cell towers, or panel antennae, that cellular companies are allowed to erect in densely populated areas. Apple is pushing high-bandwidth technologies with their iPhone and iPad, and AT&T can't keep up with the cellular bandwidth demands on a system that was originally designed for low-bandwidth voice technologies. And, to top it off, the next generation iPhone will offer multi-tasking, so you can talk or text while streaming music or video or checking your e-mail.
The biggest joke is that cell providers charge EXTRA for texting. Texting uses very little bandwidth - miniscule compared to streaming video - so you'd think that the cell providers would encourage texting.
AT&T's approach is a way of "encouraging" smart phone users to connect to nearby wi-fi networks to avoid using cellular connections. People who were about to unplug their high-speed Internet at home and share their cellular connections with their computers are going to have to rethink that idea if AT&T is their provider.