Girdler, I still have my super old 'talk' plan that does not get changed whenever my contract is renewed... I doubt a contract renewal will force us out of unlimited data... I'm more concerned about my unlimited data not having LTE and the new phone is anticipated to have it... maybe they'll use that to force us out of the grandfathered data plan?
I've upgraded phones on AT&T four times and haven't ever had to "update" my contract except to add data when I got my first iPhone.
If they are gong to force out unlimited with new phone activations, I'll keep my 4s for a mighty long time!
I can more than endorse that unless there is any big sudden change, non-issue. I've had the unlimited plan since launch day 2007. Been grandfathered in since things changed and I have owned every iPhone model, renewing my contract every time with no issue.