Windows Phone is growing like iOS used to. Soon, android and windows will dominate, and iOS will be a niche player, much like OSX.
The old timers will continue to use it, much like OSX, while the new buyers will not.
Just my $0.02.
So when you say "OSX is a niche player" do you mean "growing faster than the market".....because that second comment is the reality.....
As has been said, Apple would be hard pressed to out marketshare the hundreds of OEMs they are up against running Windows and Android...
Apple sells the most popular smartphone line in the world (the iPhone), sells the most popular tablet line in the world (the iPad) and sells a desktop/laptop line that is actually growing in the face of decline of the entire industry.
Oh and they own more than 2/3 of all smartphone profit share, and the iPad accounts for some absurd percentage like 90% of all tablet internet traffic.
Let me ask you, if you ran a company which would you rather have.....5% of market with 70% of profits or 95% of market with 30% profits.....
Apple isn't going anywhere.