The assault charges against singer and actor Kim Hyun Joong have not yet been proven. For now, they are only allegations. But if the singer is found guilty, it seems likely that his career will suffer, as k-celebs are held to a higher standard than Hollywood stars.
The closest case to compare it to might be actor Park Shi Hoo"s 2013 date rape scandal. The allegations damaged his career even though the charges were eventually dropped. He has not worked in Korea since the charges were made early in 2013. The news that he might be cast in a drama even after the charges were dropped prompted so much negative criticism that his involvement did not happen.
He has worked outside of Korea but it might be a while before Korean audiences accept him