Your party at this point in the game consists of an animated suit of armour, a floating skull, a man permanently on fire and a steampunk robot. Plus yourself, an immortal, intelligent zombie (sort of).
The chances of a sequel ever appearing are pretty much zero, since Wizards of the Coast shut down the Planescape D&D setting shortly after the game was released and have subsequently heavily retconned elements of the setting in the 3rd and 4th editions of the game. In addition, with the D&D rights lying with Wizards and the Torment rights lying with Interplay, navigating the legal minefield to be able to make the game in the first place would likely be time-consuming and complex.
For this reason, Torment's lead writer, Chris Avellone, has been musing on the idea of doing a 'spiritual successor' to the game, but not an actual sequel, for a while. He's told Kotaku about some of the ideas he and his company, Obsidian (the successor to Black Isle), have been kicking around. This includes maintaining a non-traditional fantasy setting (no elves, dwarves etc), having a small, focused cast of supporting characters and bringing back an overhead, isometric viewpoint.
Avellone, whose other credits include Knights of the Old Republic 2, Fallout 2, Fallout: New Vegas, Neverwinter Nights 2 and Alpha Protocol, is currently working on Wasteland 2.