Growing the fan-base doesn't rely on going to historic tracks, as you only 'discover' the historic tracks once you become a 'fan'. By that point you're already sold into the whole thing.
Bahrain, justified or not, has done more damage to growing F1's fanbase than alternating with spa will ever do.
When I think of F1 now, I think of the emperor's new clothes. People are just starting to see F1 for what it really is.