I was going to reply in with a cute and quirky comment like, "With roles reversed I'd be playing an I-Box and listening to an X-Pod."
But as I was reading the posts I see a growing misunderstanding of Windows machines.
I think the main reason why Win "dominates" (I use the term loosely) isn't because of their upgradeability, access to more software, or familiarity. Its really a combination of alot of factors. A 16 year old can make a killer gameing rig, but his mother can still jump on it and use it like her work PC. When it comes to Windows/Mac debates, I constantly hear Mac guys say there is just as much software out there for Macs. Unfortunatly this really isn't true.
With the internet, yes the Mac world is continuely gaining strength because finding software and help is much much easier. But, it still doesn't mean there is an abudance of software out there like there is for Win. Yes in the big picture, you can basicly find something that will work for whatever you need with a Mac, but with a Win machine you can find 5 programs that will do what you need, giving you a choice.
Now don't get me wrong, I like Macs. The Macs are up there as some of the best looking computers you can buy. But a big problem is Mac is the only major company that makes Macs, while there are many companies in the Win/PC buisness.
But back to the roles reversed discussion. The original poster seems to believe that Macs don't fail, which isn't true either. There would be the same amount of jobs in this world, Hardware, Software, Programing, Servers, Networking, etc...
In a roles reversed world, the roles would litterally be reversed, Mac would get all the new programs first, the company would look like Microsoft, and Microsoft would look alot like Macintosh company, in the world's eyes.
But something tells me that even if the roles would be reversed, they really wouldn't be. People like to tune their Pcs, and tinker with its settings, and completely build new Pcs, and put Linux on them Dual-booting, and all the other little hacker things people like to do. People would get tired of feeling like they had to buy an entirely new Mac to play the latest game, when a small upgrade would do just fine for a Pc.
I think no matter how it gets twisted, Mac will always control the multi-media and editing side of the game, and Pc will always control the Buisness, Gaming, and casual use side of the game.
Both systems really lend themselves to their specific catagory and both system can cross into the catagories they don't control, but neither of them are solid in catagories they don't specialize in.