I guess it depends on what part of the country you are in-- like all forms of just about everything. In the Mid- Atlantic states, 1/8 is alive and doing very well, while the 235mm class is dying a slow, painful death. In other parts of the country, it's just the opposite. I beleive the fastest growing class overall is the 200mm nitro sedans. We have plenty of 200mm and 1/8 racers to keep many tracks (within about a 2hr drive) very happy.
However, I will admit that I think the hobby would probably double in popularity if there were more permanent racing facilities. Parking lot tracks are just too much trouble to keep going.