To get to 25% market share they'd also have to be the largest computer manufacturer on the planet. I guess at some point though - 15%? they might be happy enough to licence to other manufacturers though.
Now that they have come out with Boot Camp, my theories are in array.
My thought was that with sales in other divisions rising fast, the hardware sales would become a smaller part of the total. If Apple had done what I had hoped they would do, which was to buy the programs Corel let go, and possibly bought MacroMedia, when they put themselves up for sale, they would bias themselves towards software, multimedia distribution, and consumer devices.
After a couple of years, the computer hardware division might comprise less than 25% of the total. with high profit software sales, and large volume CES devices, they could then think about Licensing the OS to other companies, such as Dell, which has expressed an interest.
This way, even if Apple lost 50% of their hardware sales it would be made up in the much increased royalties from other manufacturers, and the sales of OS upgrades, as well as the increased Mac software that would go with the increased sales of "Mac's". As that loss would be perhaps 10% of total sales, it wouldn't be a problem. The increased sales from everything else that would result would far more than offset it. This would certainly lead to an great uptake in X. Even if some piracy resulted.
The situation today is vastly different that it was when Apple allowed clones, back in the dreary, gloomy days of the early '90's.