I disagree. T-ara is third most popular Korean girl group in Japan. They're still profitable in Japan, unlike many other Korean artists who debuted there. But I wouldn't be surprised if J-Rock decided not to renew the contract (which was a record-breaking 4.3 million when they signed it) due to Hallyu wave dying and T-ara's scandal. When T-ara signed with J-rock they were on the path to becoming the second biggest girl group in Korea (and Asia) after Girls' Generation, but after the scandal they were knocked down to mid-tier.
Still, I think they are profitable in Japan and any agency would be lucky to have them over there. Especially now that their Korean popularity is rising again, and Hyomin was able to headline her own Japanese movie.