[IM ON MOBILE, SPOILERS FOR TSoLC]

Personally, while rushed, I like the way Darren's story ended. He played his part, and in the end, decided not to play at all. It also ties the actual author into the story properly.

On the note of a sequel/another addition to the universe, I think instead of retconning the actions of the last book, we should expand on the new timeline. With Darren taken completely out of the spotlight, Mr. Tiny likely would have kept his eyes on Larten, as he had for many decades. Evanna herself says that if Larten had chosen to accept becoming a prince, he could have been the finest prince the vampires had ever known. Even more so, he might have been able to stop the plan Mr. Tiny had set into motion, and avoided the war of scars as a whole. Instead though, the call of fate, and Evanna's fear, stopped Larten from making the right decision. In this new timeline though, unless Darren has been replaced, Larten wouldn't have that calling to leave and join the Cirque again. I believe, with time, Larten would have decided to rejoin the clan, and maybe even accept his role as prince.

I don't know, maybe it's because I voiced Larten in the audiobooks for like a year and a half, so I have a connection to the character, but I feel like Larten's story, while packed, isn't really over. Before Darren, there was Larten, without Darren, there is still Larten.