https://source.android.com/docs/setup/contribute/licenses says most of the Android userspace is Apache 2 licensed. While they can’t close source the Android branch of the kernel, they could close-source new userspace code and it would probably diverge from the last open source release quite quickly.
Realistically, that would probably be sufficent to make Android functionally closed-source, even if the GPL bits were still available.
Google can decide all they want, but they can’t close source Android due to the GPL.
https://source.android.com/docs/setup/contribute/licenses says most of the Android userspace is Apache 2 licensed. While they can’t close source the Android branch of the kernel, they could close-source new userspace code and it would probably diverge from the last open source release quite quickly.
Realistically, that would probably be sufficent to make Android functionally closed-source, even if the GPL bits were still available.