There's thousands of small unheard of search engines.
However, if it was ti happen every url would still be accessable so business could still carry on as usual but I think it'd only no less than a week before a new, well built search engine popped up.
What I'd like to know is how it effects SEO, hmm...
I think that companies such as Google would get a bunch of people suing because they're paying for their links to be at the top and things as such, when Google is down that doesn't happen.
Also as others said before, something else will pop up and I'm sure off the internet media (newspapers, tv) will guide people to new search engines