According to the article linked in below, the reporter asked, "With Cyworld recently making a dramatic comeback, the domestic social media scene possibly faces another change. What will be the next game-changer?"
In my opinion, this will be really challenging for Cyworld. In 2000's, the most important reason that Cyworld dominated the Korean blog market is that it was the first and nearly only blog platform provider at that time. But nowadays, blog market was perfectly changed in Korea. There are many blog platform providers in Korea. Many people already use other blog platforms such as KakaoStory, Facebook and NaverBand. In order for Cyworld to make a success story again, it should make a attractive difference from other blog platforms but I guess that it wouldn't be an easy task because people tend not to change their usage style easily.
resources : http://www.koreatimes.co.kr/www/news/biz/2015/11/123_189796.html