No offense, but I dont think you thought this through because you seem to be contradicting yourself. At first you said you want a "compact camera with an APSC-sized sensor" and that it would entice Canon/Nikon gear owners to ditching their gear. But then you say it should be a micro 4/3 yet to avoid the "issue with lenses" they should use a fixed focal length?
It seems that this discussion isn't about "serious photography" because you aren't necessarily looking for the best camera in the market, but rather that you simply want one made by Apple.
So if the discussion is "Wouldn't it be cool to have an iOS camera" then from the Prosumer market's perspective I would have to say "No".
Pros:
- iOS is super easy to use
- Apps for doing on-camera editing
- Wi-Fi/Phone Tethering opens up many social sharing capabilities
Cons:
- iOS is TOO super easy to use. I love my iPhone but I want a lot more controls
- Touchscreen doesnt lend itself well to the fine tuning of physical dials
- iOS camera experience is "good enough" but far from "ideal" or "easy"
- Battery drain would be unbelievable
- A fixed lens (your idea) limits the iCamera even more than any P&S
- Pricing would be somewhere between Touch and unsubsidized iPhone ($500?)
- Apple doesnt know glass
- Apple doesnt know sensors
- Apple doesnt play well with 3rd parties
- Apple isnt good at giving proper updates to its "hobby" projects
Again, Im not saying Apple would be bad at this market, I just think they're smart enough to know not to bother. But, IF you're looking for a way to expand your personal photography on an iOS device then why not just get an Ollo Clip?
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iPhone Lenses: Ollo Clip