I think having a massive fan base really just helps to speed up the launch of something, and it doesn't determine success in the slightly longer term.

With a new and great product, you have an exponential growth curve. People find it, think it is great and tell their friends and so on.

The only difference with having a fan base built up already is you get to start further along the curve.

It's still the same curve though. And how great the product is determines the shape of the curve, not the fan base.

In my opinion anyway, for whatever that may be worth.