According to Indian site GameGuru, Rare is busy working up a sequel to the original Nintendo 64 game. While the article is posted in broken English and cites only "sources," it does say that the sequel will be a darker take on Joanna Dark and will introduce a morality system where the choices players make branch the storyline. The plot will apparently be unveiled entirely through the player's perspective without cut scenes.
GameGuru says an official announcement will be made late next year. IGN contacted Microsoft for comment but was greeted with the standard "Microsoft does not comment on rumors and speculation" line.