To me, the most promising alternative to C are actually alternatives to GCC and Clang, which don't use "undefined behavior" as a wanton license to rewrite your program to do whatever they feel like at the time. See for example the cproc compiler that I linked to in the article. And, as someone who still writes heaps of C code, I feel like undefined behavior is an over-stated problem. I run into weird C issues pretty infrequently. Memory safety does cause issues more often than undefined behavior, though. Unintialized values, use-after-free, buffer overflows, I run into these more often than I'd like. Usually they're pretty loud, though, so it's apparent that there's a bug somewhere, and tools like Valgrind make dealing with them pretty straightforward.

It helps to remember that you're not clever enough to do clever things, in any language. The other most promising alternative to C is just doing it more conservatively.

Also, the Rust Foundation just looks to me like a corporate mouthpiece, not unlike the Linux Foundation, which will do little to nothing to make Rust better for anyone. 10 directors and 1 developer, what a recipe for success!

Aside: I'm working on a new programming language which I hope will be interesting with respect to these ideas. It's being kept private while it's under development, but anyone who is interested in this problem space should shoot me an email if they want to hear more.