Yes, the problem is mobile users, both the sheer number of them as well as their data demand growth. Think about what's next on the horizon. Every vehicle with mobile IP constantly exchanging data. Pandora radio in the front seat while the kids stream Netflix movies in the back. Video chat everywhere as texting is viewed as something akin to Morse code by the young. That's where we're heading and all of this is technically doable today--except for the lack of sufficient mobile bandwidth which needs to grow at a furious rate to keep pace. Metered usage is what will help fund this growth.
“Pandora radio in the front seat while the kids stream Netflix movies in the back.”
That is a good point. I tend to forget about video in vehicles. A few hundred vehicles within range of any given POP could put a congestion load on a T3, I suppose. Although why would somebody rely on a wireless connection for streaming realtime video in a moving vehicle rather than downloading ahead of time and just playback when driving ? Kids typically watch the same movie over and over again, after all.