I don't think he will sit it out.
Why should he? Just to look bored again and don't even getting to sing? I think they will say something like this: "Akanishis still in Japan but he's busy practising for his concert in L.A." If they mention him at all. He's not on the cover, he's not singing...as far as I understand Akanishi is non existant for this single and that also means promotion wise.