Holy ****, it's amazing how no one has any idea what they're talking about.
You know that Altera makes FPGAs, right? The ARM chip is there to drive the FPGA, but the FPGA is the primary product. There's a reason that Intel is fabbing for an FPGA company, and that is because they don't compete with Intel's other major customers and it doesn't cannibalize Intel's other business.
The only thing this means is that Intel is testing the waters for fabbing. The fact that there's an ARM chip there means essentially nothing. In fact, Intel already fabs ARM chips for other reasons, so this isn't really anything new.
Would Intel ever fab ARM chips for Apple? Probably. Would Intel ever sacrifice it's x86 business with Apple just so it could fab Apple's ARM chips? Never. That would be more work for less profit.
I don't even understand why anyone would want an ARM powered Mac. There's a crazy huge performance difference between the best ARM processor and an Intel Core processor. You want significantly worse performance so Apple can make even higher margins on its computers?
Also, the issue of merging iOS and OS X is misunderstood. You don't have to merge the codebase, they're already the same code. It's an issue of compilation, and not so much an issue for Apple, but an issue for all the 3rd party apps that are already compiled for x86. When moving to a less powerful architecture (Intel->ARM) you're not going to have a lot of success running all those apps in an emulator.