Google has 90% search market share--Comcast doesn't have that even in areas where it is the sole high-speed wired provider (because DSL and cellular are viable alternatives for a significant part of the population). And over large swaths of its service area it isn't the only high-speed wired option. I don't know where you're located, but I've lived in Chicago, Atlanta, DC, Baltimore, Annapolis, New York, and Philadelphia over the last decade. Each place except Baltimore has multiple providers. And Comcast competes with cellular
everywhere.
If you take the view that cellular or DSL aren't legitimate competition (despite having double-digit marketshare even where Comcast has no other competition), then Bing and Yahoo! aren't competition for Google either. In which case Google has a nationwide monopoly in search.
