I thought you said you think of nips as an ogre, I mean onion
I suspect there will be many new ways to fetch notes in the future (p2p overlay networks), etc. nip01 just defining the packet is good.
I picture nips branching out as a tree. Maybe there is a root node that defines social networking nips, that specifies the outbox model as the way to fetch notes for that class of applications.
So in that sense I agree with nostr:npub1acg6thl5psv62405rljzkj8spesceyfz2c32udakc2ak0dmvfeyse9p35c if this is what he means, but there will be other root nodes for other application domains with different ways of routing notes.
Discussion
Onion tree
Just realized this analogy is basically the same, with the root of the tree being the center of the onion. There could just be multiple onions.
onions don't fork, that's garlic