http://www.investopedia.com/articles/markets/030416/googles-...
That said, if they haven't diversified by the time the need for Google's search engine disappears, or if most people start to use the service without clicking on paid ads (e.g. because of adblockers), they will clearly have problems. "They're working on it" isn't the same as "they have it" when it comes to sources of revenue.
Other than Instagram and WhatsApp.
Page 31
$2B per quarter from "other revenues", listed as "sales of digital content, apps and cloud offerings for enterprise, and sales of hardware".
$2B per quarter would be a huge business in any other context. It's just that ads is so spectacularly successful.
Facebook the company has several options to branch out with synergies and create additional revenue streams: Identity and content are the first that come to mind, but there are probably a lot more.
Overall the problem of not being able to grow, because you already have all the users is really nice to have.
Its very unlikely, but if 10 years ago if someone said Nokia wouldn't be making cell phones in 10 years ago who would have believed you.
Everyone was on AOL in the late 90s and now its mostly gone. Tech is just so fast moving I could see it happen. It just isn't likely.
Google makes many different kinds of things, making it less likely that Google will be thoroughly replaced in people's lives.