Basically the title.
I have seen the EU-OS/Suse discussions for some months now. However, Ubuntu/Arch/Fedora are extremely mature projects. So competing against them will be hard.
I want to know how realistic the scenario (described by the question) is.
It doesnt matter tbh. Even assuming they could entirely prevent non-US downloads it would take perhaps a few months before non-US alternatives were up and running. Its not like the entire worlds gonna go oh ok guess we wont have that stuff then. They’ll just host their own downloads. It probably wouldn’t even take that long. It might cause some short term chaos, but long term it wont do a thing.