America wants Japan to take responsibility for more of Japan's own military defense. So the US wants changes to Article 9 as well. Trump moreso than Obama even.
I'm sure the military industrial complex supports this very wealthy nation being freed from its spending constraints as well.
The ink on the constitution had barely had enough time to dry when the US began pressuring Japan to repeal it. There certainly will not be any change to the constitution while Akihito is emperor, and I predict there will be a huge scandal when his son inevitably comes out against it.