AT&T has never had unlimited data. They just lowered the limit from 5GB to 2GB. That being said, I sure hope we see it.. and I hope they apply it to my now endangered 5GB plan
I'm getting really tired of having to watch my data usage the 4th week of every month.
Actually, they have had unlimited for years, and I've been on unlimited since I started with them back in 2006. You can still get unlimited data for feature phones and standard handsets.
I typically average around 5GB myself. Partially via tethering, partially through on device media consumption and downloading. On Android and Windows Mobile I would download podcasts, mixes, and apps for my laptop while out so that I can copy them to my laptop later. I'm not doing that now due to OS limitations, so after this first month of massive Zune Pass download sessions, I'll probably average about 3GB a month.
Regarding roll over data, I don't think it'll happen any time soon. First off, I don't know if AT&T is even able to do this en masse. And even if they are, I wouldn't expect it until a few years down the road when limited data accounts are the norm, and people have ways of watching their usage in near real time, and the *#3282# number is far from near real time. Lastly, I forsee a lot of people who mistake megabytes for gigabytes, ignore the warning texts stating they're going over their limit, and call/visit AT&T pissed. It's a lot easier for people to visualize how many minutes they've been talking versus how many megabytes of data they've transferred.