Intel Corp (INTC)

[Saturn V]

Haswell is the successor to IvyBridge(high end x86) and is only a few months away from introduction. Haswell will have power dissipation in the tablet category and much better performance than the present Ivybridge used for Macbooks.

ARM based phones and x86 based phones are "equivalent" both in terms of power dissipation and performance, although there are a lot of reviews which show Intel is better.(http://www.xtremesystems.org/forums/showthread.php?283746-no-this-is-not-the-1st-of-april-...-x86-beats-ARM-at-power-efficency-in-Tablets&highlight=Drwho%3F)
Intel will be introducing the next generation Atom on 20nm in late 2013,which may give the Atom a significant lead. The best than can be expected of ARM is that it stays equivalent to the low end x86 Atom family.

If Apple moves the Laptops to ARM it will have to perform emulation of x86 code for legacy applications,which will dramatically reduce the performance. So the performance of ARM based Macbook will fall off dramatically. The Native Macbook applications will be handicapped by moving to a low end processor, and if emulation is used for legacy code, that will be a disaster. The best way to view this is that a move to ARM even for native applications is a move away from the high end processor to a low end processor,and that gets worse with emulation. You can already see the disappointing performance of Windows RT which is based upon ARM. More than a year ago,Microsoft had announced that the RT machine was going to run legacy applications via emulation, but obviously they abandoned that approach because of the performance penalty. Apple sells to the masses by exploiting the image it has cultivated of 'superior quality'. It cannot afford to give up on performance without destroying its brand.