On 11th of December 2017, new upcoming policy for blocks will apear on Ethereum Classic blockchaing. Upcoming event is called ECIP
What is ECIP?
"Its a neccessary measure made to adopt a monetary policy that balances the long-term interests of investors, developers, and business operators in constantly growing community of Ethereum Classic users.
The new monetary policy sets a limit for the total ETC issuance. The block reward will be reduced by 20% at block number 5,000,000, and another 20% every 5,000,000 blocks thereafter. Uncle block rewards will also be reduced. Due to variations in the reward rate of ETC, we anticipate the total supply to be approximately 210 million ETC, not to exceed 230 million ETC."
Text quoted from: http://ecip1017.com/
This event will reduce the reward for mining ETC, as well as devaluate number of ETC available, this means that potential value of Ethereum Classic may increase in the future.