Yeah if facebook comes out with a search engine, then the things will be different, then only Google can be down!!!
The internet evolves so quickly these days, there's really no telling the future, even the very near future. I was watching some very interesting Facebook interviews the other day and many of the experts were saying, Facebook is trying to be the #1 site on the internet, including becoming the #1 search engine. They have the money and several Google engineers have actually switched sides to work for Facebook. Even the second richest man in the world, Bill Gates has faith in FB. He has invested a few 100 million into FB. I believe in the near future if anyone can overrun the King, it's going to be Facebook. At least for now, Google is still King, and there's no search engine that even comes close!
I assume that you are asking this because you made a new search engines yourself, right? For me Google will still reign as the number one search engine and there are no questions to that. its already a household name actually.
Bing is young it need time, i think that Microsoft with windows 8, internet explorer 9(the default search engine is Bing) and the partnership with Nokia(the default search on the smartphone will be Bing) may steal market to Google.
No one can give the answer accept the internet world..depends on the market. I believe it will not because Google bought so many shares and bought so many companies and added to their search engine.. if some come than they need to have there own idea and formula to bit google... Facebook is the next target...hope so.. Alam