Planet13 - 2:18 pm on Jun 14, 2012 (gmt 0)
Remember that if google were broken up or somehow lost SIGNIFICANT market share to several competitors, we would all then have to try and optimize our sites to rank better in MULTIPLE search engines.
If it is a struggle to rank well in ONE search engine, how hard will it be if you have to rank well in, say, four search engines to get the same amount of exposure to your site?
The fact that a single search engine has so much dominance is probably one of the BEST things that could happen to anyone trying to generate organic traffic (unless, of course, you rank fantastically in bing or DDG or yanex but rank poorly in google). In effect, you only have one target to hit, instead of multiple ones.