I expect it will be changed once DSP releases comeback images. That way the girls will all have the same concept, and we won't have to photoshop Youngji in awkwardly.
With all the groups listed in that tweet, I wouldn't be surprised if each group only sends a couple of members, so we may not get a chance to see all four members together.
This episode's performance brought out a lot of sympathy for Gyuri: http://www.youtube.com/watch?v=AN8nSzhjEg4
It's the Showvival episode from June 16, 2007, where Gyuri's belt waged war against her ability to concentrate on the song and dance.