SATA is an end to end packet based network so this could be done. People did make networking drivers for SCSI systems and Firewire and USB networking devices are commonly available. I think you could do it with normal cables and cards that support port replicators which some built in hardware on mainboards do. However, you would have to write your own drivers.
While this might be an interesting intellectual hobby it would be a lot of work for very little value. SATA has only a short cable length and a small amount of replication. Gigabit Ethernet is vastly superiour in all ways except for a theoretical speed cap.
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