I just recently cut phone service to my home when I dropped DSL in favor of cable internet. I think this trend will only accelerate in the next few years:

According to the US Consumer Expenditure Survey from the Department of Labor (DoL), the percentage of households paying a mobile phone bill but not a landline bill rose from 0.4% in 2000 to 7.8% in the first quarter of 2005, and later in 2005 the National Health Interview (NCHS) survey also estimated that 7.8% of adults lived in households with only a mobile phone.

Pew estimates that Americans who rely solely on their mobile phones now make up between 7% and 9% of the population and they are significantly different from landline users in many ways.

I really think 911 service will be the tipping point. Once people are confident that they can dial 911 and be located as easily with a cell phone as they would be with a landline then they won’t have a problem switching. There’s no point in paying two phone bills a month when a cell phone does everything you need.