The main problem is, I think the author is wrong about what Google's "crown jewel" is. Yes, Google has a huge index, but most queries aren't in the long tail. Indexing the top billion pages or so won't take as long as people think.
The things that Google has that are truly unique are 1) a record of searches and user clicks for the past 20 years and 2) 20 years of experience fighting SEO spam. 1 is especially hard to beat, because that's presumably the data Google uses to optimize the parameters of its search algorithm. 2 seems doable, but would take a giant up-front investment for a new search engine to achieve. Bing had the money and persistence to make that investment, but how many others will?