ETC's block reward pays for a certain amount of mining to happen. If demand for ETC and its price stay about the same, then ETC's block reward won't change. Nearly all of the miners who quit mining ETH will find it not profitable to mine ETC. (If they all started mining ETC, then the reward would be split too many ways, it wouldn't be profitable for anyone, and people would exit until the reward was split less.)
https://news.ycombinator.com/item?id=32844350