The 'market share crown' corner of the market is, by definition, not a niche.
OS X accounts for about 10% of the computer market at last count from The Register. They're the niche player, and you're 100% right that they're in the niche everyone wants to be in but the idea that the people who account for 90% of the market are suddenly going to give up and go home (which is the point Orlowski appears to be making) is absurd.
Apple have done exceptionally well to define their markets and build a moat that is very tough for others to bridge which is how they can reap their super-normal profits, but in order to stay there they're going to need to keep taking risks in redefining their products to stay ahead and my contention is that that's going to get harder as mobile technology matures and $100 phones become good enough for most people.
As for the idea that Google find the current situation unpalatable. I see no evidence that they do. Google's search product is by far their priority number 1 and keeping the 'market share crown' niche (sic) protects them in the new world. Making money on Android directly would be nice, but it's not their priority.