I'd have to agree with some of the others, it really is all dependant on the location and the current economy.
I've been doing nitro on-road and electric off-road for about 4 years (7 really but I dont count the last 3 due to college taking up my time). When i raced the parking lot track by my hobby store there were easy 20-30 racers, last year I visited and there were only about 12 but all but 2 ran nitro. I've been talking to the hobby store crew and it seems that this year they have a huge increase in both electric and nitro racers coming in to get there cars ready for the summers races again.
Who knows maybe both sports will gain a boost this year. I hope so cause I too am getting back into the swing of things
And I also think that the whole "Green" argument is just a convient word for people to use because they are simply -too inconvienced- by the sound of our fun... poor babies