Entrepreneurs, the people who need to be found have a massive need right now not being met via google, it has for many simply become a burden they can no longer afford, someone will step in to fill that need. That is how markets work. I was having this discussion the other day with someone and they agreed that small business owners will indeed work around almost any obstacle, he noted the proliferation of "sign wavers", people hired by small business to stand on the road with signs. Now to me that right there has giant market need written all over it.
You have a near tyrannical entity with google imposing its will on the individual spirit, that just won't last, no how, no way. Most small business owners I speak with actually hate google. That will shortly translate into market solutions.
There is another end to the market that I haven't seen discussed and that is the cost to consumers. Some verticals are currently taxed at the rate of 40-50 bucks a click, bringing their cost of a good or service sold through the google gate to 4-500 dollars. That cost is passed through to the consumer. I do expect the consumer or "user" would move to a cheaper venue if one existed. The whole notion that a bing or a duck-duck can operate a "me-too" ad model is flawed, there is no compelling reason, as measured in dollars for the consumer to switch. Someone fires up a nickel click engine allowing the advertiser to pass through the savings and heads will roll. You may not achieve world dominance at a nickel a click but you can certainly operate a bang up search engine.