Date: 2015-03-01 20:10 (UTC)
From: [personal profile] mindstalk IP Address: (184.108.40.206)
The webcomic A Miracle of Science had a big groupmind on Mars. Alastair Reynolds had the Conjoiners, who are like cuddly and more fleshed-out Borg. So I'd say not completely out of style.
[Not completely, but rather less common than it used to be.]
I fan-spin the Unison Devices of "Nanoha" as being a full merge of minds and memories, at least in the cases of full unison like Hayate/Reinforce and Signum/Agito. I've got various fic ideas exploring that, also an ability for Hayate to dip into and share minds with her knights. That wouldn't be always-on, though.
[I'm not familiar with "Nonoha."]
Julian May didn't get into what the coadunate metapsychic mind was really like, and she's older than the other two, if not as old as Sturgeon.