Ethereum (ETH) is clearly winning the battle over Ethereum Classic (ETC).

http://slacknation.github.io/medium/13/13.html
The above link is the most important graph when regarding ETC/ETH. The hash rate ratio and price ratio rise and fall together. At it's peak, an ETC coin was worth roughly 45% of an ETH coin (not pictured on the graph I linked because that updates every 30 minutes, but at one point in that interval it reached .45), but this was mostly due to hype, and the hash rate during that time was more than 10% lower, so the price was untenable.

The price and hash rate graph does seem to be offset somewhat, sort of similar to how a sine curve and cosine curve reach peaks and valleys at differences of pi/2. This is explained because miners and investors are working based on economics. Miners see the price rise and change what they are mining, while investors see the hash rate low, consider the position untenable and sell. Then the graphs reverse. As of this moment, the hash rate ratio is 19.42% while the price ratio is 23.64%, meaning we can expect the hash rate ratio to rise and the price ratio to fall.

Now, if you notice, the overall trend of the graph is downwards. This is mostly due to two things:

1. ETC is not a traditional pump and dump like other altcoins, but it's price rose rapidly mostly due to hype, and after a few days when hype dies down, the price drops as well
2. The Ethereum Foundation and many important developers in the industry all side with ETH.

Interest in ETC will probably always exist, but over time it will decrease, especially when combined with the fact that ETC will have to do its own hard fork down the road when dealing with Proof-of-Work to Proof-of-Stake switches (or in the altnernative case, a hard fork will need to be done to defuse the difficulty bomb)