My understanding is this (correct me if I'm wrong...) is this is exactly the business model that has killed Vorbis. Xiph originally created a floating-point free reference implementation, and charged for the integer decoder. You pretty much have to use the integer decoder for any sort of hardware implementation, so the effect was the same.

With few users and a paid barrier to entry, few hardware vendors took the leap. No hardware support means fewer people bothered to encode to Vorbis... and the spiral to the bottom continued.

If you're trying to use the network effect to your advantage, you do exactly what the MPEG-LA has done: the first couple of years are free, then everyone pays. The only want to combat that is to do the same.