Eternal Sonata extra characters Xbox 360?

I recently got an Xbox 360, and my first game is Eternal Sonata. I'm almost at the end and I found out that the PS3 version had 2 extra characters, Crescendo and Serenade! I had a PS3 first, and before I bought it for Xbox 360 I was thinking... maybe I should get this for PS3... but I decided to get it for Xbox 360. Does anybody know if Crescendo and Serenade will be playable in the future for Xbox 360? If it will be downloadable from the Xbox Marketplace? HELP!