Riku ia not Sasuke, he's more like sai or Armin. The only similiarity is they are in the dark side but Riku ia not antagonist toward Sora.Kairi is the aqua or new aqua of this since kairi is her seccsor. Let's hope cause I think Riku knows sora and kairi are meant be together.
Yup i think kairi Will get action. Maybe her side kick is mini and Daisy.