I am a fan of your work as well. I took both your BD course on your site, as well as the playmaker one through Udemy when I was first starting out. Everything you listed sounds good to me. Certainly XML or other data storage sounds interesting, maybe anything about online multiplayer integration, or even score boards, etc.
You might want to make a simple email sign up sheet, so people can subscribe to your course. Then when it comes out, you can let people know it is available.