Apple, like other premium brands develop a following that will pretty much buy the product whatever. The underlying products (and they actual products as this does not work for anything else) are of good quality but the brand has an exceptional marketing machine that means people are prepared to pay significantly more than the actual development and production costs. One of the important skills is being able to charge what the desired market will stand and where possible ruthlessly push the envelope upwards as your user base gets drawn in. Apple is interesting in the way they have been able able to develop this in a consumer environment where the economies of scale have given them a license to print money.
Other brands or products that have been successful are:
DuPont with Corian worktops & Amtico flooring, both use cheap raw materials turned into good quality expensive product that was market at a premium. This made it desirable and people both expected to pay a high price for it and when the cheaper alternatives appeared, would shun them because of the brand.
The same could probably be said for some car brands:
Porsche, Bentley. Bugatti, etc, maybe even Rolls Royce.
Miele, Maytag appliances.
The crucial thing is that as an earlier post states, people will continue to buy the brand where they can and pay the premium price tag because they are prepared to. They want the product and for tech, it needs to be a current version. As long as the product broadly continues to deliver what they need then the customer is happy and the company rakes in the money. This takes us back to the marketing. In the grand scheme of things marketing is cheap for these people but is a crucial investment to maintain the brand position. Apple have changed CPUs before and probably will do again. The fact that most people simply don't care what the CPU is as they use a basic set of preinstalled or easily installed software is the winner. It just needs to work.......
Maybe I am wrong but having sold some of these products and understand what goes into make them, marketing and pricing for what the consumer is prepared to pay accounts for a lot.
If this move by Apple were to upset the majority of their customers then they would take a hit but they will recover because it is unlikely it would be so bad that people deserted the brand in the long term.