>I don't think they can legitimately fall back on the "but we can't support it otherwise", since they already do. The cost of developing new iOS builds is amortized by the hardware they sell and the profit they rake in.
Those costs are amortized over the hardware sales specifically based on the current revenue model of the iOS platform. If you force a change in the model, or force them to produce new APIs and SDKs they had no intention of making and therefor no need to amortize, then I think yes they can fall back on "we can't support it otherwise".
The real simple question that has been never been answered in this entire discussion over and over again is what is the fair market value of Apple's SDKs, access to their platform and the support that provide for that platform if its not amortized over hardware sales and current revenue split agreements? Forget even trying to answer that for the entire iOS platform. If Apple puts NFC chips in their phones, and then:
1) Has to write an entire public SDK they weren't intending to write
2) That allows access to those chips outside their specific sanctioned and envisions use case
3) That requires providing ongoing support for that SDK and the uses of it outside their specific sanctioned use case
4) Expands their security threat surface for the underlying secure hardware that SDK will interact with and requires more development to secure it
How much money is that worth in cold hard cash up front per developer per update per hardware revision?