Mac OS X 10.5

There is a lot of speculation coming out of Robert X. Cringely, including some grounding from John Gruber. I’d like to comment on it.
Cringely says a new kernel is coming for Intel Mac OS 10.5. Gruber says Apple would never release a PowerPC 10.5 with a different kernel than Intel 10.5. But I am not so sure. Gurber admits the kernel of an operating system is hidden from the average user. Developers would have to test against 10.5 wether it had a new kernel or not. But Gruber does have a point, writing operating Systems kernels is hard. Just ask The Hurd.
But what if Apple decided to use the Linux kernel? They could add Mach-o as a first class executable format. They could replace the driver subsystems with IOKit, and bam! You would have a kernel in no time. This would even allow you to run Linux executables (no need to eliminate ELF). Imagine a Gnome or KDE app running side by side to a Mac app. A lot of people find that desirable.
Then Cringely talks about Apple rewriting the Windows XP version of the WIN32 API so they could run Windows applications natively under Mac OS X. Gruber notes how non-trivial this would be and I totally agree it would be to difficult to actually do.
But what if Apple used their cross patent agreement with Microsoft to “Carbonize” the WIN32 API? Pick 80%-95% of the most used calls and rewrite them. This would require Windows Developers to recompile their application, and fix any “missing API” issues. But they will have to do this for Vista anyway. There would be no reason to implement undefined behavior (or bugs).
All Apple would have to do is convince Windows developers to write to 5% of the market.