The most likely competition to google is cheapening hard disks so that things like wikipedia, siri, and entire newspapers archives sit on your computer locally and so that you can do more complicated sql like queries on it.
A dump of the current revisions of all English Wikipedia pages is just 31GB - that's less than 5% of a 750GB, which are common nowadays.
But Wikipedia and newspapers don't really have structured data you can query; except for those small boxes and some tables, most Wiki articles are just a blob of text.
Besides, Wolfram|Alpha already gives you results based on structured data by answering more complex queries than simple substring matching, but I don't see anyone using them as a replacement for Google.
