Yeah, I was kind of joking about it. Although I found some people take the idea very serious..
Personally I think Thief is done, there was a trilogy. If someone makes a new thief, just make a new game, with a new story, protagonist and possibly gameplay. Thief fans that only want pure Thief gameplay, can just play TDM. Not to say this is the only thing TDM has to offer.
Theoretically it would be really nice to see a remaster of the 3 Thief games as one Thief game,
but I think it's either not going to happen, or if it is, it will not be perfect. Putting these Thief games in a new engine, will alter gameplay, for the good, but possibly also for the bad. We've seen it before..