This idea comes from a post that was made several years ago. There was a forum member who predicted that Maeve was at Splttercon!!! disguised as the girl wearing vampire makeup and teeth that freaked out Harry and almost caused him to go into full attack mode. There was nothing wrong with making this WAG, but this forum member continued to post this idea after Maeve died at the end of Cold Days. From strictly a dramatic or story telling point of view, this seemed highly unlikely to me, because what would be the point of finding out half a dozen or more books after Proven Guilty and several books after Maeve had died that she was making moves behind the scenes at the horror convention? If you found out now that Maeve had been working with the fetches would you really care? Probably not because in the Dresden verse Maeve is dead and gone and therfore no longer has a role to play in the story. However, there is one exception, and it applies to every other dead character in the series.
Jim has said that Harry will eventually have to break all the laws of magic, so it seems likely we will get a time travel Dresden Files novel from Jim. I picture it as being similar to the Star Trek Deep Space Nine "Trials and Tribble-ations" episode, where the characters from Deep Space Nine had to go back in time to stop another time traveller from changing the outcome of "The Touble with Tribles" episode of ST TOS. However, I'm not saying Harry will go back and revist the events of Proven Guilty; though that seems like a really good guess to me, and I'm not saying Harry will learn anything new about Maeve, though he might.
What I'm asking; actually I'm asking several things, is what time do you expect, or would like to see, Harry to go back to? If not Proven Guilty, why? Which character or characters; who have joined the choir invisible, will we see Harry interact with? Do you expect anyone else to take this trip with Harry? What do you think Harry will learn or what would you like him to learn? If there is anything else I've missed about time travel you would like to discuss, by all means go ahead.