But of course, that is not Apple's only way to play the x86 game, nor is there any chance they would do anything like that in the near future. What Apple should do, and very well may do, is to port OSX to the x86, and sell it as an alternative to Windows/Linux. In other words, in the x86 world, they would be a software vendor only. They would continue to sell PowerPC-based hardware.
With OSX available for x86 hardware, software vendors with OSX-based products would potentially have a far larger market: there are two orders of magnitude more x86 machines than there are Macintoshes. Apple would have an additional source of revenue: those who prefer, for whatever reason, to use x86 hardware. Just 1% of that market would be extremely significant both to Apple, and to software vendors with OSX-based products.
The major risk would be that a significant percentage of those who would have bought Apple's PowerPC-based hardware might decide instead to buy x86 hardware (on which they run OSX). This is a risk because Apple would make less profit per unit on OSX for x86 than per a Macintosh/OSX bundle. This risk only matters if one assumes that Apple's customer count wouldn't change much as the customer base switches from Macintosh hardware to x86 hardware. But it doesn't seem likely that that would be what would happen.
OSX for x86 would not be a very popular product, even among Mac fanatics, unless and until significant software titles became available. And that wouldn't happen unless software vendors had faith in the viability of the market for OSX software on x86 hardware. So the mere fact that you could buy a CD that would install OSX on your x86 machine would not, by itself, have all that much effect on Apple's sales.
However, if there were sufficient x86/OSX software available so that those who would have bought a Mac start deciding to buy x86 hardware instead, then we're in a different world entirely. In that world, it wouldn't just be high-probablility Mac customers who would be buying OSX-x86. Far from it. There would be at least as many former Windows/Linux users also buying OSX-x86--probably more than enough to offset the per-unit profit differential between Mac customers and OSX-x86 customers.
They already have it -- without the fanfare. Apple bought NExT. The NExT technology DOES/DID run on Intel. The hub of Mac OS X is called "Darwin". This is open source and can be installed on Intel, now. (Its Mac OS X without the user interface). The user interface of Mac OS X called "Aqua" right now is ONLY available on Macs. However, the Aqua interface is NExT technology, and it can be ported to Intel with little or no bother.
Everytime Steve Jobs is to make a speech at one of these trade shows, I study at the computer rags for speculation - "Apple's going to announce Aqua for Intel" has been a steady theme- but alas, its just proving to be a rumor. It would sure piss M$ off, as M$ is already objecting to PC manufacturers shipping "naked" PCs (a PC with no OS on it) and are trying to stop this practice. M$ claims that if a person wants a naked PC they're really going to put a bootleg copy of Windows on it. A stupid argument, when there's currently Darwin, Linux, BSD, Solaris ... etc that can be put on the PC...
If Apple were to announce their Mac OS X on Intel, they'd mop up. Let's face it, Apple wrote the book on the human interface with the computer - what ever you think of them as a company, their OS work is right out of the cognitive psychology field when they studied the results of people like Miller et al and devised an OS that really took into account how people react to computer as a system as a whole.