Can companies like Google or Facebook "die"?

Violation of privacy,Facebook’s new policies make clear that users are required to grant the company wide permission to use their personal information in advertising as a condition of using the service

nothing can last ...everything nowadays is changing fast

Yes, online companies always face that risk as having a strong online presence attracts much competition. If you recall, Hi5 and Foursquare were once "It" companies, but where displaced and lost their throne to facebook. 

Great question and thank you for the invitation. Company like Google & Facebook always has risks. One Mistake can take them down, their one technical mistak can provide a way to hackers to hack and destroy. As we know hackers are always looking for famouse companies websites. Just like Apple. When there was a mistake in their maps.I'm not saying that Apple is down now , at that time they lost trust of many customers. 

Another example is Orkut. Before Facebook Orkut was very famouse. 

they wont die they just dissappear - "its all business ":)

so dont take it hard something new will come to entertaine you even they'r Gon!

yes, it happens when they failed to deliver service availability

Evolution is not only for living beings, it is for companies also. Look at used-to-be-great companies like Nokia or Blackberry. They failed to evolve and look where they are now. Change is the name of the game. So if FB and google decides to not follow the rules of evolution, they will ultimately die too. Another case in point is - Orkut. Despite the big bang entry, FB simply killed it cause FB was better than Orkut and Orkut didnot change to challenge FB. So it died. 

Change is the universal truth and if any company or an individual don't evolve according to the chaning time they simply die. It had happened for many biggies and it may even happen for Google or FB provided they don't adapt.

And history had always witness that if you are at the top, its very hard to see the ground changing. And moreover when someone is at the top, it generally leads to overconfidence too and thereby leads to mistakes which ultimately becomes the cause of thier downfall. It had happened to individuals, organisations, societies and even civilizations. So its just a matter of time.