Just for the record, I'm in at least mild agreement that search is looking increasingly vulnerable. Google are falling down here.
It's just that "search" is really a web of interrelated services, capabilities, and revenue streams, and they tend to reinforce each other strongly. I'd like to see the monopoly disrupted.[1] But I don't think it's just a matter of "build a better mousetrap^Wsearch engine." Attack one corner, and Google will snipe at you from the others.
And with the AdWords cash cow, they've got an immense revenue stream.
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Notes:
1. Well, mostly. Google's acquired so goddamned much personal data that the premise is frankly kind of terrifying as well --- a weakened Google with neither the revenues nor talent to defend that pile.... And I'd really like to see the toppling occur without simply raising a new monopoly in its place.