I personally think it would turn off a lot of Thief fans if they changed the protagonist from someone other than Garrett. I think Stephen Russel's voice acting was fantastic and added to the story and feel of the game. If you want to feel what another character would look and react like in Thief then try the fan-made Thief designed for Thief 2.

I would like to see more open ended gameplay much like Deadly Shadows hoped to accomplish but can be drastically enhanced without load times with the new technology out there. I want a choice when and where I do missions. The idea of an editor to add no areas and missions would truly enhance the game. I totally agree on the above for bringing back rope arrows. I also want to see some of the mechanist robots possibly working as serving/guard bots in mansions. Rooftop missions should also be key as that was one of the best missions in all of Thief 2 but kind of failed in Deadly Shadows. I truly hope that they do not leave the city as that is key to the Thief series and truly adds to the mystery. I want the developers to think New York city size Thief playground and then give me the missions and time to do it.