Apple doesn't care that much about market share. And that's not a new thing.
Look at the Mac PC. I mean, just face it, there are only so many people who are willing to pay twice as much cash to buy a laptop-for-the-desktop (iMac) or overpriced laptop. And yeah, I mean feature for feature... I bought one for my daughter, for college, a year-and-a-half ago. I actually got less laptop (less RAM, fewer ports, lower screen resolution, older Intel i7 chipset) for not-quite-twice the money. It would have been more than twice, but I bought a refurb, from Apple themselves.
So Apple's got about 5% of the PC market, but over 80% of the $1000+ PC market. That's a very good example of how they work. They're making 30%+ margins on Mac PCs, versus say HP, at about 5%. If Apple really cared that much about numbers, they'd have to drop their margins significantly to increase sales. In the short term, sure, they'd sell lots of Macs. But the cachet of that as an exclusive platform would fail, once it were just as cheap as everyone else. They'd need to sell about 30% of all the PCs on the planet, just to break even selling at HP's margins. And HP actually has high margins, compared to the ubercheap Chinese PCs at the very bottom of the market.
They've done basically the same thing with iPhones and tablets. The iPhone's market share is kept artificially high by the US sales model -- the average consumer doesn't see what they're paying, so they don't see the iPhone as being more expensive than other smartphones. Of course, it's a different market, but still changing... I don't think we're anywhere near the point of stability that the Mac vs. PC hit. You'll know it, of course, when smartphone news is as boring as PC news.
There is only one thing that would really bother Apple: a significant drop in iTunes revenue. That could lead to diminished support for iOS applications, and that's not the way you sell a premium priced product.
As of late last year, iTunes was still bringing in nearly twice as much of the green stuff as Google Play, despite Play having eclipsed iTunes in terms of total downloads. Now, sure, Google Play isn't open in as many countries as iTunes, but it's still an accepted meme that iPhone buyers spend more money on apps and media than Android users. So developers are going to support iOS, and they're going to support Android. Even if Android keeps improving, there's no reason to expect iOS to become a problem, even at lower market shares.
About the only real thing that could be a problem would be the emergence of a really strong other platform, something strong enough to replace Apple as #2. Does anyone really see Windows Phone, now essentially a Nokia proprietary OS, doing that anytime soon? No one else in sight even has a change... most of the other mobile platforms (FirefoxOS, Sailfish, Tizen, Ubuntu for Phones) are pretty much expecting HTML5 apps to be the norm, not much OS-specific development beyond embedded applications.
So Apple's optimizing profit, not market share, for the near to medium future. As long as that formula works, I don't think they're going to do much about their installed base. That's different than their worrying about not being a player at all in major markets. They want to be popular in China and India, not an also-ran.