Isn't that how it is already?But what happens when iPhone leaves AT&T and is now on all carriers. AT&T is going to have no reason to give early upgrades and rather just let people stay on contract and force people to wait out the normal 18-20 months upgrade cycle.
Most people I know tend to hold hold on to the phone for the normal 18-20 months any how. It is only the iPhone fanboys and girls who upgrade every year.
Only the primary line is eligible for the yearly upgrade, all other lines need to wait 20 months.
AT&Ts special 2010 upgrade policy for the iPhone 4 was announced as 6 months early but because the standard policy is 4 months early, it was really only 2 months early (assuming you signed up in Dec. 08). So it was a good policy from a PR standpoint but not much of a difference to most people.