What would we replace it with? Fiber? Quantum entanglement? Telepathy? Ethernet itself is the common-sense design you would arrive at if you needed to move bits

What would we replace it with? Fiber? Quantum entanglement? Telepathy? Ethernet itself is the common-sense design you would arrive at if you needed to move bits from point A to B. Of course, things like the connector form factor could have evolved radically differently. Maybe in a parallel universe Ethernet uses something more like a unidirectional USB plug.