It can't be happen but if one day Google will not be there, then will switch to another search engine like bing or yahoo i guess
Google will always be there in a search engine form. The beauty of google is that despite there being thousands of new search engines launched each year promising to beat google, they never do. Why? Well that's simple, when you are a market leader like google you adapt. So a new search enginee offering a specific niche may do well for a few weeks but then google will incorporate those features into it's own search engine thus gaining lost visitor back. It's the same with any new product, take washing powder for example one company ads a new gimmick and within a few months they are all copying it.