Entire web archives such as the entire dump of wikipedia and stackexchange (including media and indexes for search) can be stored locally. The missing piece is Google level search quality on the local machine. Given that brute force substring search can process Gigabytes in seconds nowadays. If you have enterprise grade server hardware things are reaching 1000GB/s. At this rate, there is no reason to think in a couple years local search of all known human knowledge can't happen on a local device at Google level result quality.
For anyone interested in the search space look into whats possible today in local offline search.