The counterfactual replacement would have been created 3 years later (in expectation).

Interesting, my reaction was that it would have taken less time. So just based on the the contribution of the search engine, I'd rate the value of Google lower, but this estimate doesn't seem to take into account the long term value of creating the kind of company that Google became -- an engineer-led haven for top talent, with the motto of "Don't be Evil."

I think that's probably more significant than a 3 year jump in search quality.