Competition for a limited resource (ad space, land, wireless spectrum) selects for companies with higher margin. In one understanding, higher profits mean the b

Competition for a limited resource (ad space, land, wireless spectrum) selects for companies with higher margin. In one understanding, higher profits mean the business is providing higher value. In another, it means the business is sucking up excess value that could be had by upstream consumers. Ad space can be seen as land rented out a user request at a time. Having more competitors to Google will help only a little bit. There's only so many user request x ad space x keyword units to be split among the companies. So the total amount of "land" advertisers bid for remains constant, so prices will be roughly similar. The only difference will be that Google will command a smaller cut of the auctioned price. I doubt that will make as much of a difference as an influx of entrants to the bidding market. Some Google keywords are 10s or 100s of dollars; the Google cut isn't driving hat, but the value of a new customer acquisition. Disclaimer: I work at Google but not on ads.