It is exactly the sort of thing that Kickstarter and the like make possible. Historically Thieve's World RPG materials were only created as a tie-in when the series was actively publishing in the 80s and briefly again in the early to mid aughts. Without crowdfunding options I'd say the chances of a 5e Thieve's World setting would be 100% if a new anthology book (or somehow a movie or something) in the series comes out during the life of 5e and 0% if one does not. With crowdfunding the revival of defunct IPs is, by comparison, quite a bit more democratic.I remember reading the short story anthology from the library in the 90's! I can't see any evidence that anything has been done with the Setting in any medium since the Aughts? Would make a cool Kickstarter, I imagine.
Do you have any idea who is doing it? And any links?From what I understand it will be a Kickstarter