Hmmm I guess it could be possible.
But with the way Ayu's popularity is taking a plummet it's hard to say.
I mean, would you really want an unpopular singer to promote your merchandise?
(Not saying anything against Ayu, just speaking from their point of view.)
But since they've stuck with Ayu for years now then it might not be a factor.
I can never make up my mind >.<