Necromunda will possibly see a new edition, possible titled Necromunda Hive (or Spire), the Death Wars. The new edition is apparently due for release July 2001.
Interestingly enough, I'm told this rumoured remake is due to fulfill two roles, both as an independent skirmish game incorporating a few Mordheim rules (for multi-level battles and the gangs' evolution) and as a supplement for Warhammer 40K. It will be like Codex Armageddon and its campaign, with special rules for battles in hives and new force organization charts (especially for bigger scale battles).
The supplement will also apparently explore the rich 40K background and move the history forward a touch.
There will also be a campaign to support the game, including the creation of a new demon (named "Athanata the Soulkeeper" I'm old) by Karloth Valois in the lowest level of Necromunda Hive and the major attack of the other Chaos demons to eliminate this new challenger of their power, the coming of a huge Grey Knights force supported by the Bone Angels (a Blood Angels successor Chapter that will turn to Chaos!) and the forces of Ecclesiarchy. It will also apparently feature the double-crossing role of a new race (Hruds), lead by Tina Ulanti (Mad Donna's sister) the Ruling Houses and the forces they can muster to support their place in the Spire, the Eldar and Dark Eldar fight side by side for some apparently sinister reason and a small but destructive force of Human-Tyranid hybrids (probably a Genestealer cult) play a part in things too.
A worldwide campaign is going to reportedly also take place, depending on success of the now running Armageddon campaign.
The book will contain army lists (and restrictions) for all 40K races currently available. Vehicles will not take part for obvious reasons, with the possible exception of bikes and jetbikes.
The book will also apparently include rules for fighting in hive spires (3D platforms, tight corridors, ladders and elevators etcetera) as you'd expect.
Now, obviously this is one of those rumours that sounds incredibly cool, but comes out of nowhere and could quite possibly be amusing the GW Studio staff no end with its numerous inaccuracies and far out nature. However, as the saying goes, rumours is rumours, and if I hear any further rumours on this subject, I'll let you know.