Hey there!
I thought about a thing that completely falls under the photo AI stuff: photo colorization.
Load a black and white photo, do some magic, and show a realistic color photo.
Yes, that kind of stuff already exists, and it works already damn good.
You can look, for instance, at the Deoldify open-source project, and some websites (like MyHeritage) are already offering services like this (based on the same open-source project), but with too few options.
I’m sure that this kind of AI-thing is something Topaz can make for general purpose with great quality. And it can be amazing.