So I’ve been using Unreal for a year now, and following Ben’s C++ course, and I did notice that there’s an EQS video, but it looks like there’s only one and it doesn’t cover how to create tests in C++. This would be good, since you can’t create them in blueprints yet. So a detailed EQS course, with how to create tests and generators in C++ would be awesome. This engine is popular with FPSers so I’m sure a lot of us Unreal fans would love it 
Another idea is a course on the material editor in Unreal. I haven’t seen any courses on that in Udemy, and there’s a lot of confusing stuff in there for non-artists like myself. You could also make a two parter, with half the course covering materials, and the other half covering Cascade.