In fact, both have been out while I have been a user. When Google went down, I literally refreshed once, it failed again, and I went to Yahoo (today I would go to Bing). When Facebook was down, I did something else, since there was no substitute for Facebook.

I think you're overestimating the chances that in the future Google will play as important a role as it does today.

Google was the first to solve the "search problem". They won't be the last, and finding information is only one aspect of one thing people do on the internet. Google has not been very good at making money in any other way. Competitors in the search engine business are emerging. I can totally foresee a scenario where Google's core business shrinks quite a lot over time, and I have a sneaking suspicion they do too. They're scared, whether they admit it or not, their acquisition spree is evidence.

> Google was the first to solve the "search problem".

Google definitely wasn't the first to solve the search problem.

That's subjective. I consider Google the first "good" search engine.