I dont think it'll be a "bonus" track . It's being released as a single and she's no Namie so it most likely will be on the album. Well ... then again, she didn't include stuck on you for some reason...
whether or not she'll do her own solo version of the song though is still up in the air but I doubt she will do that as well.
edit: well it turns out she WILL do a solo version
NEW SINGLE
あなたがいる限り ~A WORLD TO BELIEVE IN~
伊藤由奈×セリーヌ・ディオン
2008.1.16 OUT
SRCL-6696
¥1,223 (tax in)
Tracklist:
1. あなたがいる限り ~A WORLD TO BELIEVE IN~
2. あなたがいる限り ~A WORLD TO BELIEVE IN~ (U.S.A. Mix)
3. あなたがいる限り ~A WORLD TO BELIEVE IN~
(Yuna Ito Solo Ver.)
4. あなたがいる限り ~A WORLD TO BELIEVE IN~ (Instrumental)
creds:moviebuffwwc @ JPM