It does not work this way, there are only 2 version of internet protocol (TCP), IPv4 and IPv6, if you want use internet, external routing and so on, you are going to need to connect to either otherwise you aren't going to get communication. And both were controlled by the US (DAPRA controlled IPv4, IETF controlled IPv6)
There is a reason why usually it's the FBI that busted dark web (IP/Website that are not searchable) that's because US basically have exclusivity to all IP address. And you can't transmit anything outside your own network without a IP address.
So if they gone dark, that's it, they can't use it at all, it wouldn't matter if China supply Iran with router and everything. Becuase the TCP/IP is going to be the same.