The data layer is purely agnostic, meaning everything about #Nostr can work exactly as it is now, but be communicated and connections made via the DHT. (The DHT is solely for peer discovery, same as torrent networks)
The Nostr protocol is actually completely agnostic to the relay system. Relays is just the low hanging, easy method for distributing the data layer. It could run on Pear just as easily (conceptually, obviously implementation would have some hard work behind it), the only caveat being that if you wanted the Pear network and the relay network to be one global community, you specifically need bridge nodes.