I think what is impressive about Firecracker is that they have chosen to reuse a lot of the right things (Linux/KVM/Rust) while also taking a new approach and rethinking important assumptions (No BIOS, no pass-thru, no legacy support, minimal device support).
In my opinion the Firecracker FAQs give sufficient mention to parallel projects and tools they have built on like Kata Containers, QEMU and crosvm. The developers certainly seem open to collaboration with those communities.
AWS doesn't have much of a track record in terms of leading an Open Source projects so some skepticism is understandable, but I think what we have seen so far is a very good start.
In fact we are considering integrating a more secure language than C in QEMU, even though we're just at the beginning and it could be C++ or Rust depending on whom you are talking to. :) It's possible that this announcement could tilt the balance in favor of Rust, add it would be great if QEMU and Firecracker could share some crates.