> most Linux distributions are just cosmetic variations of the largest upstream distros.

Plenty are not. I am impressed by how usable community-based (non-corporate) distros are (e.g. Gentoo, Arch). This is truly indigenous technology.

> they all rely on Torvalds and everyone else for the kernel (heavily funded by donations, companies, etc)

This is an interesting thought. I believe the Linux kernel would continue to be viable on a purely volunteer basis, without corporate subsidies; I can't prove it though.

I suspect you're right, but it would certainly be a tectonic event, and could potentially affect Linux's competitiveness until equilibrium recovered.

And you're right about "most" being wrong. "Many" would have been a better word, particularly if talking about the most popular.

(Another non-upstream-reliant distro that I find fascinating is GoboLinux. Very against the grain/orthodoxy!)

Without corporate subsidies, corporate subsidies would soon reappear. If it's useful enough, corporations will pay to continue having it.

Kernels aren't any more important than compilers, xorg, user space utilities and so on. That Linux managed to get its name on the whole stack doesn't mean much. You might as well be complaining that linux distributions are vulnerable to power outages.

If anything the major distributions are defined by their package managers, of which there is a large and healthy number - aptitude, dnf, pacman, protage, and a heap of weird and wonderful other ones with minuscule usage.