Multiple save the G petitions have been created in protest, and Public Advocate Bill de Blasio started the Five Stop Fan Club, which argues that the G extension helps local businesses. As a resident of the area, I personally feel like two years of the train not going to my station with no shuttle buses and no decrease in my fare has earned me the right to a few MTA dollars.
Members of the Kensington/Windsor Terrace yahoo group are suggesting a new tactic: arguing that the extension isn't an extension at all, but a restoration of service. According to an MTA map from the 70's, the G train used to run all the way to Church. This 1974 Map shows the G in its previous "extension," while by 1978 it has been trimmed back to Smith-9th.
Of course, nearly all the train routes have changed since the 70's, and some of those changes make a lot of sense given ridership patterns and budget realities. Still, historical precedent is now on our side. Don't call it an extension: restore the G train to its former glory!