Nope, putting MacOSX on Intel would be a really bad idea.
I think that Sun provides a good illustration of the best case scenario when it comes to Solaris. They've got an x86 version, but software support for it is really weak, and the hardware support is even worse. Solaris/x86 is hardly used anywhere it matters, and it's performance is simply horrible compared to the Solaris version.
So, the best we could hope for with MacOSX/86 is weak software support, weak hardware support, and a collective yawn from the entire Intel-machine owning public. Besides, remember that it's very very difficult to purchase an Intel-based system without Windows on it. In this picture, the question becomes, "If I have to pay for Windows, and it's already on the machine, why would I want to pay again for MacOSX (with fewer apps available for it)??" In fact, this is one of the problems that Linux faces right now.
Another possible (and worse) scenario is that, as you suggest, it would somehow bring more software to OSX. If everyone suddenly stopped buying Apple HW, instead buying x86 machines (to run all this OSX/86 software that's supposed to suddenly appear), it would gut Apple's system sales, and then there'd be no Apple, no MacOSX, and we'd all have to run Windows or Linux.
It's going to sound strange, but Apple is not in the business of selling Operating Systems. They're in the business of selling systems - not just hardware, not just software, but the whole package. MacOSX is simply a component of a larger system called Macintosh. Take either the OS or the hardware away from the equation, and you'd quickly find that it doesn't really stand very well on its own. Running Linux on Mac hardware, for instance, is functional, but not at all the same thing as running Macintosh (MacOS on Mac Hardware). The same would be true of MacOSX on non-Mac hardware.