This assumes that we can get a locked down, secure, stable bedrock system and sandbox that basically never changes except for tiny security updates that can be carefully inspected by many independent parties.
Which sounds great, but the way things work now tend to be the exact opposite of that, so there will be no trustable platform to run the untrusted code in. If the sandbox, or the operating system the sandbox runs in, will get breaking changes and force everyone to always be on a recent release (or worse, track main branch) then that will still be a huge supply chain risk in itself.
> This assumes that we can get a locked down, secure, stable bedrock system and sandbox that basically never changes except for tiny security updates that can be carefully inspected by many independent parties.
For the most part you can. Just version pin slightly-stale versions of dependencies, after ensuring there are no known exploits for that version. Avoid the latest updates whenever possible. And keep aware of security updates, and affected versions.Don't just update every time the dependency project updates. Update specifically for security issues, new features, and specific performance benefits. And even then avoid the latest version when possible.
>Which sounds great, but the way things work now tend to be the exact opposite of that, so there will be no trustable platform to run the untrusted code in.
This is the problem with software progressivism. Some things really should just be what they are, you fix bugs and security issues and you don't constantly add features. Instead everyone is trying to make everything have every feature. Constantly fiddling around in the guts of stuff and constantly adding new bugs and security problems.
The secure boot "shim" is a project like this. Perhaps we need more core projects that can be simple and small enough to reach a "finished" state where they are unlikely to need future upgrades for any reason. Formal verification could help with this ... maybe.
https://wiki.debian.org/SecureBoot#Shim