Answer=NO

If Google closed its doors tomorrow there are major competitors ready to step in and take Google's place.

Answer = YES

Google's demise would cause major economic upheaval. Many businesses, ours included, are dependent on AdWords and organic search. Others to a lesser extent, AdSense.

However, in a short period of time this could always be migrated to Goggle's successors in the event of a failure.

Google is not a financial institution that would require governments to step in. If Google failed tomorrow there would just be a scramble ( a simple commercial event ) to migrate to the other major players in the Search Engine Industry and Internet advertising products.