The flagship communities are quite alive, but the niche communities have not really taken off. I am talking from both the absence of such communities, and my experience trying to migrate !fluidmechanics. The subreddit has around 10k humans (or bots).
If it is a pay what you want model I am all for it. This would be similar to how elementary OS st
The problem with a fixed price is you have to always calibrate it according to the economy of the user’s geolocation. What is cheap for a person from a developed world may be unaffordable for a third world county.