The problem is that government is being used to choke out the competition, especially at a local level: http://www.wired.com/2013/07/w...
Comcast uses government regulation as a shield to block competition. So yes, the libertarian solution would be to remove these blocks and open up the options.
And you are naive to think that anyone in government, especially Democrats, will regulate Comcast. Obama has been in bed with Comcast for a while http://thehill.com/policy/tech.... And Comcast owns NBC, which owns MSNBC--the Fox News of the Democrat party.
Sorry to bust your Government/Democrats good Republicans/libertarians bad bubble.