Does anyone with insight into Git development know if we should care about this? Is this just a proposal out of nowhere from some rando or is this an idea that a good portion of Git contributors have wanted?
In a brief search, they’re engineering manager for GitLab, appear to be a frequent contributor of high-difficulty patches to Git in general, and are listed as a possible mentor for new contributors.
Given the recent summit, it seems likely that this plan was discussed there; I hadn’t dug into that possibility further but you could if desired.
Looking at the comment thread, at least one person I recognize as a core maintainer seems to be acting as if this is an official plan that they've already agreed on the outline of, if not the exact timing. And they seem to acknowledge that this breaks some of the more obscure platforms out there.
rustc_codegen_gcc is close to becoming stable, and conversely the Linux kernel is dropping more esoteric architectures. Once the supported sets of architectures fully overlap, and once the Linux kernel no longer needs unstable (nightly-only) Rust features, it'd be more reasonable for Linux to depend on Rust for more than just optional drivers.
However, adapting the conventions and mechanisms of a large complex C system like the Linux kernel to Rust is taking time.