Summary
Apple made no promises about unauthorized modifications and therefore doesn't owe anybody anything when it upgrades the Iphone.
Analysis
Apple did sign an agreement with AT&T and now others in Europe to provide exclusivity of the Iphone to these carriers. It is incumbent upon Apple to enforce this probably as a condition of the contract if not just for the sake of keeping their partners happy. Apple has an unprecedented deal with carriers in that they are the first device manufacturer to share in the revenue stream. why would they do anything to jeopardize such a sweet heart deal? So breaking hacked phones is just a nuisance part of QA for a software release.
If an Iphone is hacked and becomes useless after an upgrade then its too bad for the owner. Nobody at Apple signed any piece of paper or made any announcement that hacking would be supported. And those owners are a tiny percentage of the Iphone customer base. There is no difference between putting the wrong charger on the phone, throwing it in the ocean or hacking in terms of a voided warranty.
So for 99.99% of the world the fact that Apple does not support intentionally damaged phones is not an issue.
