It's already out there. On people's local computers and soon their mobile devices. People are tinkering with it at warp speed. This point addresses that it technically cannot be stopped.
I don't expect it to be possible to detect that the art is AI-generated. This becomes further impossible when using a personal input image as well as many follow-up edits or composite works. It blends into normal image creation. The only way to prove that it's not AI-generated is to record in-progress "human art" as is sometimes done in art contests, but this isn't reasonable to legally require of every single piece of art to be created.
You can't enforce what you can't detect.