What will cause Apple to be in danger later this year with the iPhone Air and AIRc ?

About what? None of those are real products at all. We can’t make any statements about magical unicorn dust simply because they don’t exist.

I doubt Apple will be in danger any time soon.

I think people need to stop with the feature predictions, and the specific feature "needing." So many people are using iPhone 5 and 5S models, and yet are loudly proclaiming they "need" a larger screen. A lot of these are probably the same people who years past said they "needed" NFC payment method support, or Galaxy-esque NFC handset-to-handset data transfer, and yet today, hardly anybody is even discussing it anymore.

When the next iDevice is announced, just ask "is this new device useful to me? Are other devices MORE useful to me?" And be honest about it.

I for one don't want a bigger screen for the sake of having a bigger screen, and if it FEELS like this is happening with the iPhone 6, I actually might not upgrade to it. The increase in size has to be for a reason other than size envy alone. I see no value in a phone that is bigger than my hand - or worse, bigger than my face - if someone can't specifically tell me why doing that is a good idea. And bragging about pixel counts and physical dimensions alone is NOT a good reason.