Rust has the same control over memory layout.
And Cyclone used a GC; it wasn't as minimal as you think. The stuff needed to actually get rid of a GC while maintaining memory safety (retaining dynamic memory allocation) didn't really get developed in a practical way (IMHO, anyway) until Rust came along.
Sandboxing is orthogonal. It so happens that some of the techniques of OS-level virtualization overlap with those of sandboxing on Linux, but Docker is nonetheless not a security tool.
Not that Docker's current libcontainer work is even at all portable. It's questionable what the current ruckus about companies backing the Open Container Project will lead to.
I'll let Theo take it from here:
"You are absolutely deluded, if not stupid, if you think that a worldwide collection of software engineers who can't write operating systems or applications without security holes, can then turn around and suddenly write virtualization layers without security holes."
Right people, right tools, right architecture, and right processes for knocking out defects. That's what it takes. Virtualization's well-studied enough to tackle it. Only one's trying in FOSS that I'm aware of are L4 community: esp TU Dresden Nizza architecture w/ L4 Linux, OK Labs OKL4/seL4 / OK Linux, and GenodeOS on Nova microhypervisor or OKL4. Google separation kernel, Nizza and Genode architectures to see what I mean.
The research OS space is mostly doomed to languish in obscurity, but it seems like MirageOS just might stand a chance.
That isn't to say that IllumOS and Zones are perfect, but if something that robust can be implemented in C/C++, we can do the same or better in Rust.
I agree a modern take supporting mainstream deployment tech would be a great advance. The language itself might need to be modern. They'll reject Ada, LISP, etc. I liked JX just because there were many Java developers plus various verification tech on Java subsets. Figured Java-2-native was only shot before Rust, Go, and SWIFT showed up. Things are indeed starting to happen. :)
On the other hand, it must be noted that there's a ton of subtle timing-related attacks in crypto where low-level control of memory layout strongly benefits their mitigation [1]. I don't know how mechanisms provided by languages like Rust fare into this, though C has definitely been tried and tested well.
Then the idea of moving away GNU, the Linux kernel, Freedesktop projects and all the other myriad software from C is a pipe dream, anyway. It might have been attainable if something like Cyclone won out which extended C only to a minimum for security purposes, but otherwise the task is immense.
[1] https://cryptocoding.net/index.php/Coding_rules