As much as I love OT15, I don'tt Kibum and Hangeng would perform with sj. If Kibum wanted to, he could've done it before. He's still on SM, just be happy for him for being an actor. And about Hangeng, his career in China is soaring high compared to his status when he was still on sj. Some Knetizens even call him traitor (though I believe he's not.) I doubt they'd accept him if he comes back. Just be happy for him and respect his decision to stay in China.