By not understanding the interface, I ended up creating a "blog post", and won't repeat the contents here. But I would be curious to know what people think of the following goal: creating a way to have future core Internet routers "host" multiple side-by-side internets (virtual internets if you like), each with its own properties and each isolated from the others. On the physical layer. (See attached article from 10 years ago)
I used to debate this with GENI folks, and am interested in hearing your thoughts. One community argued (back then) that anything anyone wants to do needs to work in a tunneled mode; physical multiplexing would not be needed in that world view. My view is that to achieve QoS or true route independence for fault-tolerance one needs to be able to see the links directly and to know that if packets are emitted with certain QoS properties (like packet spacing), the routers won't mess those up.