I think Apple will rather consider screen size as the selling point. Consumers looking for either a 4.7" or a 4.0" will have almost similar configurations.
$450 for 4.0"
$450+$100 for 4.7"
$450+$100+$100 for 5.5"
Screen size would make the most sense to base pricing on. But I don't think Apple is ready for that just yet.
Here is Apple's lineup right now:
$650 - 4.7" - iPhone 6S - A9 - Touch ID, Apple Pay, 3D Touch
$550 - 4.7" - iPhone 6 - A8 - Touch ID, Apple Pay
$450 - 4.0" - iPhone 5S - A7 - Touch ID
Some people think the iPhone 5SE should just replace the iPhone 5S. But in my opinion... it will be WAAAAY too powerful of a phone at $450.
It's got a smaller screen... sure... but it's also got the guts of the CURRENT iPhone including A9, Touch ID and Apple Pay.
That doesn't seem like something Apple would offer at only $450... would it? (though it would be great for the consumer)
At $550... I could see the iPhone 5SE being comparable to today's iPhone 6.
Do you want a smaller screen but a faster processor? Or do you want a larger screen but a slower processor?
But if the 5SE was launched at $550 in march... what happens in September? We think the 6S would roll down to the $550 price-point. So in that case... the 4" iPhone 5SE
and the 4.7" iPhone 6S would be the same price with similar internal specs. That seems odd too.
In short... $450 seems too low of a price for too good of a phone. But at $550... it will have difficulty fitting into Apple's current and near-future lineup.
Here's the bigger problem: Apple doesn't WANT to sell a $450 phone. They hit that price-point only because they keep older models on the market... and because they know most people will opt for the current phone instead.
But when they start making "new" $450 phones... or at least acceptable $450 phones... their ASPs will drop dramatically.
That's why I don't think they will ever offer the same new phone internals in three different screen sizes.
That would put the starting price of "the iPhone" at $450. That's not what they want.
The iPhone has held its price for many years... though other Apple products experienced massive price-drops over time.
The 13" Macbook Air started life at $1800... and now you can get it for $1000.
But new iPhones have been $650 for quite a while. Could that be coming to an end?