No, they wouldn't. This has been analyzed out the kazoo many times and your conclusion is wrong. Apple's model is better.
If they were selling OEM versions of OS X at the prices that Microsoft sells OEM versions of Windows, Apple would have to sell 90 million copies every year, capturing 45% of the PC market—just to break even with the profits they are currently making selling just 10,000,000 Macs a year... not counting the profits from the iPhone and iPod sales.
“Apple would have to sell 90 million copies every year, capturing 45% of the PC market.”
Just to break even, you mean, to keep up with the profits they are making now? Profit wise they are a niche company and will always be so with this strategy. What happens if Windows 7 reverses the trend and they start to feel the pinch? As it is they are dependent on Windows releases.