Birth by Sleep So...is Ansem the Wise in this or what...?

I'd say there's a good chance of him showing up. After all, they do go to Radiant Garden, as we've seen in the scans. Since its ten years ago, it probably takes place during or just before Xehanort's apprenticeship. Meaning that there is probably a chance we'll see the original 6 members of the Organization before they became nobodies.

And I doubt Ansem would be young. He seems to be in his late 40s in KHII, so he'd probably be mid-late 30s.

 

Remember He Died in Kh2

 

>.> umm dude this game takes place 10 years before KH1 :P