Hate to point out the obvious, but there would surely be at least _one_ bright spark at each of the top 1,000 companies who'd think of taking Microhoo's $1m offer to Google, to see what they might be prepared to pony up by way of a counter-offer.
At which point, things would begin to get extremely expensive for both Google and Microhoo, they'd each land half of the companies for a hell of a lot more than $1m each, and we'd end up with a Balkanized nightmare of a search world where the meta-search engines would come back or you'd have to run every search through three engines to get all the results you want. Or go to one of the somewhat dodgier search engines which would be bound to pop up in such a world, which wouldn't offer anyone the opportunity of delisting.
Gee, thanks for the awesome future vision, Mark!
I'm no fan of Google, but the above don't sound much like an improvement.