I'm an embedded engineer, who's been tinkering a bit with learning Rust; so far only for an application-level project, but am keen to try it out in embedded. So far, it's been fun and exciting, along similar lines as Bryan wrote about in the OP. In fact, a video of a talk he did (https://www.youtube.com/watch?v=LjFM8vw3pbU) is what pushed me to getting started.

I think you're spot on with regards to tooling being a major concern, and to me, this is one of the promising aspects of Rust, with cargo at the high level and the LLVM tools lower down. It seems like a system that's primed for open source libraries targeting specific families of chips, cleaning up the mess we've got now with each vendor having their own framework, IDE, configuration tool, etc.

Speed and size concerns though, seem to depend a lot on the specific project. In the last couple years, I've worked on systems that had neither/either/both of those as the primary challenge. Of course in embedded, where you try to save money on parts early in a project can determine the technical (and so, schedule) challenges later on.

And, I'd add safety to the list, having spent loads of time finding bugs in legacy C caused by stuff like walking off the ends of arrays, jumping to uninitialised function pointers, fun with enums and unions, etc.