Nick Douglas disses some of the recent supposed Google killers (like ChaCha, Search Wikia and Tall Street):
http://valleywag.com/tech/search/is-one-of-these-eight-search-engines-the-next-google-hint-no-255748.php

I think the real google killer is their own ego and pride.. that will be their downfall...

Other entities can't really match up with Google..

Internet is not fashion, is not air, it is still begining business. I think there are too many chance beyond Google.