In 2010, there were quite a few smartphone platforms: iOS, Android, Blackberry, Symbian, WebOS, Windows (CE or Mobile or maybe both; can't remember when the switchover happened), Bada, probably some others I'm forgetting.
Between then and now, the story, aside from slight eddies such as the dismal failures that were Ubuntu Touch and FirefoxOS, has been one of platforms steadily exiting the market. So now we basically have just two options: Android and iOS.
And already I see people on HN occasionally predicting that iOS is doomed due to the fact that it has ~15% global marketshare, and Android has all the rest. I'm not sure if that's really true, but, regardless, the trend is still most certainly not toward a robust, competitive market with lots of consumer choice.