Your point about reliability is fair although doubling the capitalisation of a carrier would make a significant dent. However I think you overestimate the inertia of the status quo.
1. Apple doesn't need to relaunch AT&T, Sprint or any other network it simply launches a supplementary branded network like Virgin mobile.
2. The current unlimited data plans are only unlimited in the face of limited data utility. Where people can use massive amounts of data (i.e. the iPhone), unlimited comes at a premium.
3. Although Apple is revered for its high end products its iOS marketshare is 41% iPod touch and most of its device sales come from low end products like the iPod touch and the nano. It's now no stranger to mass market affordability.
1. Apple doesn't need to relaunch AT&T, Sprint or any other network it simply launches a supplementary branded network like Virgin mobile.
2. The current unlimited data plans are only unlimited in the face of limited data utility. Where people can use massive amounts of data (i.e. the iPhone), unlimited comes at a premium.
3. Although Apple is revered for its high end products its iOS marketshare is 41% iPod touch and most of its device sales come from low end products like the iPod touch and the nano. It's now no stranger to mass market affordability.