Have you actually READ the link you posted?
Times have changed a bit since then, you know ...
Yes, I have. Several times. Things have changed, but the base premise of the article still applies - Microsoft Got Lucky - there is no way to suggest that Apple can pull that off in this day in age when the world depends too much on Microsoft. The article deals with past actions affecting the present. Its very relevant. Its point is that MS got successful because of how it parlayed successes over time, not because it embraced an "open strategy". They did that years ago. Read the whole thing. Grueber makes a point that still applies today because marketshare in the OS world has changed very little.
Due to Apple's grown popularity (if not ubiquity) it can be safely assumed that quite a few more people would install Mac OS if it were officially supported on non-Mac hardware. A highly significant number of people? Good question. To Apple's benefit? Probably not.
Popularity is irrelevant. Going up against Microsoft is suicide. Period. Their market share is too large and Apple's success is too dependent on hardware sales. Microsoft's objective is to rule the roost. They did that way back in the early 90's and they are too well entrenched to be taken out directly. They are just too big. You are simply conjecturing without any basis in reality. Apple tried the cloning market and it failed because people by in large do not want to undertake the massive pains to go to a completely different platform without somewhat of a safety platform. People want Windows because the stuff they run on depend on it. Thant and competing with Microsoft directly is a folly - going up against MS is going to be very bloody. You have better luck elephant hunting with a pea shooter.
Take a look at any other market that involves hardware and software. The article makes a good point about video games. They are totally incompatible with each other and are very closed systems. They remain successful because they can take one success and transition it to another - like the Mario franchise. MS did the same thing with computers years ago (with the objective of being really lucky thanks to boneheaded decisions by IBM). Apple did not. Of course Apple's objectives were far different back then, but Apple operates differently than MS does.
While Apple could get a few more customers, it just wouldn't last. There is no reason to think that it would or that they could sustain it. Its about making a good choice.
You cannot say that Apple's market strategy would gain them more money from copying MS business strategy, you just can't because they aren't the same. You cannot make a flawed assumption and think that Microsoft got achieved success by doing things the way the market was meant to be. They didn't. Microsoft got real lucky and rode on the coat tails of IBM business mentality and got massive market share because of that - way back in the 80's. That's just how things ended up. Doesn't mean that it works that way all the time and there is no reason to suggest that Apple is gonna want to chance it.
At this point in the game Microsoft has won - Jobs has admitted that years ago. Microsoft makes billions from the business market that by in large has no interest in making a risky and expensive change that going to Mac entails. Microsoft provides a very prediction, safe route that has massive industry support. Apple would have needed this kind of success really early on - but back in that day, they were adopting practices that were fundamentally different.
It doesn't matter that Apple's system is better - the lions share of the market made their choice years ago and that market doesn't tolerate direct competition. In Microsoft's world - they are the only game in town. And I say that the reason is that Apple is still around because they don't encroach into Microsoft's big markets. They don't license their software out to Microsoft's partners, they don't sell office software to PC's. There is a reason - Microsoft is far too big.