Let me explain why I said this "I'd guess that by 2012 Mac OS will evolve into a hybrid of legacy desktop features plus iOS multi-touch and mobile features."<snip crap>
FFS, please shut up with the bullcrap, you don't have the slightest idea on what the hell you're talking about. There is no replacement for Intel, A4 is of a particular design for mobile devices and thus would never be suitable for a general purpose CPU that professionals and consumers demand for. The iPod, iPad and so on are complimentary devices and in no way replace the traditional ways in which people do their work on - anyone saying otherwise is a grade A moron that is completely out of touch with reality.
Apple's focus on iOS has been to get it to the point of being mature and all features that the majority of users need exist within iOS - in other words it has been head down bum up for the last several years to establish a comprehensive platform to which the value component, namely third party developers, can then cater their applications for thus spurring development further and sales numbers go up.
The rebalance that has happened is with the release of XCode, a gradual merging of Mac OS X and iOS development so that developers can target both platforms and hence have the same code base with different front ends based on the requirements needed. If it is a touch environment it will have a touch based interface and if it is a desktop application it will assume a traditional mode of input.
The cold hard reality is that iOS has now matured at 4.2, it has released feature completeness as so far as features demanded by the bulk of users so now the focus is on building Mac OS X and iOS so that the two work with each other, and rallying developers around both platforms to spur the development of third party applications by both platforms. There is no great mystery here, no magic, no special person hidden behind the curtain, just a company getting the two platforms to the state where there can be continuity between the two platforms - and maybe we'll see a harmonisation of release schedules at the most between Mac OS and iOS.
As for those people claiming the death of MacOS X and the desktop at the hands of iOS, the cold hard reality is that Mac OS X sits at Apple's future vision of an interconnected home where the desktop computer is still relevant. The personal computer has hung around because of its flexibility to attack almost any task so I doubt that purpose built devices based on a narrow scope of requirements are going to suddenly replace designed for multiple uses.