The cost to comment on a live network is indeed an obstacle, but it is my belief that when a comment costs money, users would naturally be more careful in choosing the right words etc. to get their point across without unnecessary spam. Hopefully this leads to more meaningful discussions?
In essence, what you are saying is 0x60 will become something similar to a paid forum where members will have to subscribe in order to interact or reply to posts. I don't know how will you promote this site to potential users when the whole internet is used to freemium models.
May I suggest that you consider the BETA with Ropsten ETH as the live one? Meaning if there are at least 1,000 - 10,000 users in beta, you port the content into the live one. Kind of like "post now while it's free."