I think it'll be easier to have one network that's secure (or, at least, securable) at the protocol level, than two networks. As someone notes down-thread, people don't like dealing with two highly-separated networks, and if you have devices on both then that's a huge threat vector.

Further, I think states are likely to use this both to prevent beyond-their-reach nationals from attacking infrastructure and citizens, and to curtail foreign astroturf propaganda efforts.

The ID stuff is something I don't think all states will adopt, but some might, even in Democratic states. I think adjusting backbone routing to allow easy network-wide black holing based on verifiable origin, though, is very likely to become widely adopted over the next couple decades.