It's delay line memory. It was common back in the days of vacuum tube computers.

A little bit, but normally Token Ring didn't just keep data running around in a circle on and on

Token Ring works more like a roundabout, where you enter at a given computer on the ring and then exit at another device. Without looking, I suspect that, like Internet Protocol packets, Token Ring probably had a TTL (time-to-live) field in its frames to keep a mis-addressed packet from forever running around in circles.

Also, I'm assuming that an implementation of Carmack's idea would have only one...I don't know the right term, might be "repeater". You need to have some device to receive the data and then retransmit them to keep the signal strong and from spreading out. You wouldn't want to have a ton of those, because otherwise it'd add cost. On Token Ring, you'd have a bunch of transceivers, to have a bunch of "exits", since the whole point is to move data from one device to another.