I think I get it now. It's not so much "Parallels" as it is "Yesterday's Enterprise," which takes place entirely in an alternate "What If" universe that branched off at some point from "our" timeline.
DS9's "The Visitor" was another example of this, giving an entire story over decades of Jake Sisko's life, only to erase that entire timeline at the end.
Also, the final episode of Voyager, "Endgame," threw the entire "canon" Trek universe into an alternate timeline. (In the original timeline, the Voyager was in the Delta Quadrant for many more years, and Seven of Nine was killed after marrying Chakotay.)
I think a series of Trek novels set in the timelines of these actual episodes would be interesting.
We could see the Federation at war with the Klingons ("Yesterday's Enterprise"), Starfleet abandons DS9 after Sisko's death ("The Visitor"), or the Voyager continues its journey through the Delta Quadrant for decades ("Endgame").
We could even see how the Alpha Quadrant's history would be altered if Earth had been assimilated by the Borg in 2063 ("ST: First Contact").
There are already many divergent realities depicted in various Trek episodes, which would make great settings for new novels, immersed entirely in those realities.
There's no need for authors to invent new timelines. (Though if this is an ongoing novel series, both original timelines as well as those seen in the above mentioned episodes, could be used.) I think it would add an extra connection to the Trek universe if readers actually remembered some of these alternate timelines from previous episodes (even if the characters in the story aren't aware of other realities).
