The actual legal IUP T&C states we have 14 days to turn in the previous phone. I've posted the link above, see the IUP page on store.apple.com (footnotes) for it also. So, at some point, it will be normal for us to mail it back in. They just haven't gotten there yet.I've read through a lot of the posts on this thread and I feel your pain.
I think the logistical issue is that somebody has to physically verify that the phone you are turning in to be replaced is in sufficiently good condition. That means either a trip to you local Apple Store (which can be far away for some) or mailing in your old phone and waiting to receive some sort of credit once it has been looked over.
Somebody high up at Apple decided:
1 No, we're not shipping out new iPhones before receiving the units being traded in.
2 IUP participants cannot even select 'ship-to-store'; they have to select from store stock.
3 Units to be replaced cannot be mailed in; they have to be physically inspected at an Apple Store.
What's in the contract fine print for IUP?
What I *surmise* will be the process is because every new phone is a new loan, the old loan won't be cancelled until they receive the old phone in good condition. Or perhaps they will charge an AC+ 'incident' to it if it's in bad enough condition to need to be replaced.
But in any case, there is nothing in the T&C that prevents us in the IUP from never stepping foot in a store.