I can see cases for moving to ARM, and also plenty of reasons against it. Still, the reasons for moving to ARM are pretty compelling:
1) Control over the product release pipeline. Fact is, Intel had to delay the release of some major mobile processor releases, and this has impacted Apple's ability to release new mobile laptops in 2014.
Also, Apple can control the performance improvements of their chips. For instance, let's say they come up with a completely new layout for their Macbook Pro that is thinner and with much better controls, they would release a smaller performance improvement for the processor, knowing people will still upgrade for other reasons. Then next year they could release a processor that performs significantly better in hopes that many will upgrade again.
Having complete control over the release of their products with a reliable product map would be huge for Apple.
2) They could reduce costs. By developing their own specs for a chip and then having a foundry make those processors to spec would decrease costs instead of purchasing Intel processors in bulk. This would allow Apple to reduce the cost of their computers, costs which they could pass along to the consumer while still maintaining huge profit margins. If the ARM transition is handled correctly, they could see an increase in sales and profits as a result (not to mention market share).
3) This could allow Apple to move towards a more uniform OS for desktop/mobile devices. To be clear, this would need to be done without making the mistake Microsoft made with Windows 8, but I that should be possible. Just some ideas:
a) They could make their desktop a fully compatible version of IOS and allow this desktop version to work with existing apps. They could integrate into the keyboard common functionality with apps to further encourage use of apps on the desktop. Instead of releasing a new desktop OS that is compatible with a small number of apps, they could have an OS with a very compelling eco system from day one.
b) They could allow universal mouse/cursor support in IOS for both mobile devices and obviously the desktop version. They could do this by integrating mouse cursor movement into the existing home button. If any company could do this will still keeping existing functionality of the home button, Apple can.
Ironically, having such a feature would allow even better apps to be released, and also provide an extremely compelling reason for people to upgrade their iPhones/iPads. I know I would want to upgrade both in a heartbeat if I had this functionality and more capable apps to go along side it.
This would allow developers to essentially release the same versions of a product for both mobile devices and desktops. Obviously this would cause fragmentation, but it would also cause counter fragmentation as well. Adobe photoshop could be designed for both mobile/desktop devices with much similarity, and the main differences would really be focused on the different screen sizes.
4) This would make Apple's product line and eco system even more flat/linear. Each device would further compliment the other. I could buy a word processor for my iMac, and also use that same word processor on my iPhone with similar functionality including cursor/mouse support. Again, I have to emphasize, if done well, this could cause customers to have huge motivation to upgrade their iPhones/iPads. Apple already has larger screened iPhones, now they need compelling ways to utilize those screens while also encouraging upgrades. The fact this, this is a legitimate way to do so without seeming like a tight-ass with 16 gigs on lower end devices, etc.
5) Essentially allowing desktop level apps to work in iPhones/iPads would allow Apple to make a truly compelling multitasking solution for mobile devices. And, they would have a good *reason* for doing so. We've all seen lame examples from Samsung on uses for multitasking on their phones. Fact is, Samsung's multitasking is a solution looking for a problem. With Apple, as the only company with such a compelling eco system, they could have a *real* reason for multitasking support, do it better then their competition, and allow true desktop level multitasking.
This would have the advantage of allowing Apple to release some compelling ads through their marketing department that would show software capability no competitor could match. Imagine the same app being show on an iMac, iPad, and iPhone all with the same functionality. Imagine, for instance, a powerful version of Photoshop that can be used with similar functionality on all Apple devices. Fact is, this would be something the competition could not touch. Only Apple could do this, if they moved to Arm. Gosh, the more I think about this, the more excited this makes me.
Now somebody will argue with me that having desktop level compatibility on an iPhone, for instance, would make for less compelling reasons to get an iPad, for instance. To that I would say, you are absolutely correct. There already *are* people who use their iPhones exclusively for all of their computer needs, and having similar capabilities on the iPhone would only encourage more people to do this.
But this would be easily offset by additional sales for the iPhone. Fact is, as iPhones become more powerful, there become less compelling reasons to upgrade an iPhone. Simply put, major innovation is needed over the midterm to continue to encourage more sales. This would certainly be the type of innovation that could further iPhone sales, and even chip away at market share of competitors.
Also, since this would strengthen Apple's eco system, there would be customers who would be encouraged to buy a desktop, iPad, and iPhone since all three have advantages. This would further Apple's sales in all three categories. Heck, Apple might even be able to make the Apple Watch useful, and further sales in that device. As an example, you have a Microsoft Word document being edited by multiple parties at different locations. I decide to go to the mall and get some Starbucks, and while I'm sipping my Mocha, my iWatch is notifying me of updates to that document. I call on my iPhone and discuss those changes with the iPhone to my ear, but I still have a second screen on my iWatch that is continuing to update the changes as they happen. The possibilities are endless when desktop level software integrates with mobile software.
I could go on with this post and continue to come up with reasons/ideas on why it would be a good idea to switch entirely to ARM, but I think you get the idea. I was going to post the barriers/reasons why a full ARM lineup wouldn't occur for Apple, but I don't feel like I'm technically qualified to do so, and also based on the reasons I outlined above, I simply think the reasons are so compelling Apple would do everything they could to overcome technical obstacles to make this happen. I don't see how they could resist!
To summarize, one microaritecture to rule them all. One micro architecture to sell devices, and in the night SPITE them!
