So, karaoke? I really hope we get one of a few scenarios, though all of them are equally unlikely:
1) World of Pain or Living Dead(Whose game release would coincide with a Cineria release)
2) a Shinkan Shoujo song (So that we hear a bit of their song before those voice bank designations of theirs are used, if they get used at least)
3) the/an idol(')s(') version(s) of Sora (So that we know that they have at least thought of the girls singing it, if not releasing it with Kotori)
4) one of Jupiter's songs (We've heard some of the girls do Koi wo Hajimeyou in a radio thing before, so I think it'd be funny)
5) one of the 876pro songs (With all the 876pro references in the anime, it'd be nice to hear the idols sing their image songs)
6) one of the Radio songs (They're just so forgotten: FO(U)R? Aishita Aishiteru? 1, 2, 3?)
7) songs from the new Cinderella Girls CD's (To reference it as still being a part of the iM@S universe. And so we can hear Chihaya sing Koi Kaze or Never Say Never)
Notice that only one scenario uses songs the idols originally sang. A few would mean new or original songs, and the rest would be covers of existing songs. Why do I want one of these? Because it's Karaoke. The girls shouldn't be singing songs they sing normally, since that would just defeat the purpose. I included the Radio ones because I want them somewhere in the series, but it's the most doubtful one of all. Mix and match scenarios to taste, since Chihaya, Haruka, and Yayoi aren't likely to pick the same song, though using scenario 7 would allow for a good mix as far as explanations go.