Why is that so many people have this monomaniacal obsession with Apple market share? The objective of Apple (or most other companies) is not global domination--there is no real advantage to having 100% market share, so why should it be a goal?
People may confuse the drive of any company to grow with the ultimate destination being full market saturation, but that's not how business works. There is an implicit need for balance, and all companies strive for that optimal point. Business development follows a Phillips Curve model--it will maximize revenue based on available resources (lots of low-margin products vs. fewer higher-margin products). That doesn't mean that 100% (or even 10%) market share is a goal.
All market share reflects is the relative rate of growth. It doesn't mean anything. Apple market share could theoretically fall, even as sales increase. Apple will go for making the most money--that doesn't mean increasing market share. If they can make the most money by focusing on a few products and selling them to a loyal base, that's what they're going to do. If market share goes up, attracting more developers and customers, that's a great bonus.