I find this question very hard to answer. I don't know that there is any one particular thing that we need -- just a steady accrual of resources, as well as the simple matter of gaining more experience in teaching Rust to more diverse groups. It definitely took us some time and iteration to come up with our current methods of teaching Rust, and we are constantly trying to tweak and improve them.
I personally believe that Rust -- or a language much like Rust -- could be a really great first programming language for people. I'd like people to learn the idea of ownership and resource management from day one, before they get used to the idea of omnipresent pointers and aliasing.
(Many people who have not yet tried Rust seem surprised when I say this; I think they imagine that, when you don't have a GC, a great portion of your time is spent worrying about how to manage resources. I at least don't really find that to be the case in Rust: mostly I just write code, and the rules kind of guide me towards what is going to work.)
Anyway, I definitely think that we should be working hard at figuring out the best ways to teach Rust to all audiences. Besides growing Rust, it also has the effect of getting us to think hard about the "essence" of Rust, which can help us to improve the language itself.