Remixes were updated on the official site.
Missing (Dubscribe remix)
Melody (BROKEN HAZE remix)
Seems like they're going to be dubstep according to the artists' SoundClouds. Dubscribe seems to mention a 'domestic dubstep anthem' when referring to Missing's remix.
http://soundcloud.com/dubscribe_produkt
Dubscribe @_Dubscribe_
浜崎あゆみ/Missing(Dubscribe Remix)は、 オリジナルがまずスケール感あるすごくいい曲だし、ベース作りも自己最高ポテンシャル出たと思ってるんで、 国産ダブステップのアンセムになるんではないかと…。なるかも…。なるといいな…。ならないか な…。
http://soundcloud.com/brokenhaze
http://instagram.com/p/Q4FZGtCDW_/
Guess they aren't Orchestra like Song 4 u. Maybe in the next CD release?