I always thought that an adult animated series focused on a young adult Toph would be entertaining as hell. The Harley Quinn series is hugely successful, and Toph is already a character who we know would be super vulgar in canon if the show weren’t for kids. A more adult show focused on her in the city, running her school, trying to figure out life in a changing world, etc. could only be good. It would probably veer into It’s Always Sunny or Jakcass territory, but I’d watch the hell out of that.
A more selfish reason I’m saying this: I’m super bummed that we have literally no canon material of the gaang at an age where I can relate to them
Edit: In before “But what about the Korra flashbacks”–no, she was middle aged by then. I meant like 20s to early 30s.