I think Korea will definitely benefit from having back their starting sette Sa-Nee but they're very weak at the middle blocking and opposite position. I don't think Russia or Serbia will have any problems with them outside of containing Y.K. Kim.
I wouldn't say those positions are "very weak". Left-handed Hwang (?) is not that bad as Opp, she's rather short but still attacks well, even from backrow. She might not be an Opp who can consistently score 25+ points but Korea doesn't need that beside Y.K.Kim. In MB they can have Se Young Kim and Dae Joung Yong (please forgive spelling errors ), both are very experienced players who are in NT since almost 10 years, they might also not be among the best of the world but I really think if Korea can combine their efforts they have a decent chance of finishing top 3. They will probably qualify also if they are not in top 3 because most likely Japan will be there so Korea would still be best Asian team besides them, but if both finish top 3, Thailand also would get a ticket instead of teams like Cuba or Serbia who will most likely finish ahead of Thailand but might miss top 3 because of Korea...