If you follow Google at all, you'll know that their big business is search and ads. The two go hand in hand. Every time you perform a search on Google.com or even their competitor, Bing.com, you see ads alongside the search results as well as a couple at the top. This is Google's bread and butter. While Google has their hands in a lot of other businesses, their profit still lies in ads. In 2014, around 90% of their revenue came from ads. Their other products are just ways to serve you more ads and use their products more. That's another reason why Google doesn't have ad blockers in the Play Store, unlike Apple.
comScore recently released some numbers regarding the market share for search engines in the month of August. And Google actually lost a bit of market share. They are currently sitting at 63.8% market share, after losing 0.2% to Microsoft's Bing in the month of August, who sits at 20.6%, with the others being even lower. So Google doesn't really need to worry just yet. However if this continues, then they will need to find a way to maintain their market share and their ad revenue. Or they are going to start charging for things, that could include charging their partners to use Android. Which they currently give away for free.
Mix this decline of their market share along with the recent rise of Ad Blockers like Ad Block Plus and things may not go all that well for Google in the next few years. Especially since ad growth is supposed to stall in the 2014-2019 time-frame. The biggest competitor Google has is not Bing, in terms of search. It's actually social media. About 30% of traffic sent to news sites in 2014 were from social networking sites like Facebook, Twitter and Google+. And that number is only going to rise. Making it all the more puzzling that they aren't doing anything at all with Google+ these days. How will Google combat losing market share when it comes to search? No one knows, but they need to do something as this trend is only going to get bigger and bigger, as more and more people find stuff through social media instead of search.