House Orlock - were one of the gangs in the original starter box (along with Goliaths) and have been traditional allies for House Escher. While not street scum or muties, Orlock are workers, the every man of the Necromunda world. In look they traditionally have a love for the bandanna and long loins clothes!
House Van Saar - are very different. They are the rich kids, with money to spend on augmentation and the best weapons money can buy, in fact other Houses prize Van Saar weaponry highly. The look of Van Saar is similar to the suits worn in the Dune movie - close fitting with thin piping, almost membrane-like!
Now things may have changed in the fluff from then to now, but we wouldn't be surprised to see a link between the Mechanicum and Van Saar and for Van Saar to potentially be a bit more techno-organic than their original incarnation. House Orlock could probably also do with a new look, so it will be interesting to see if they are still seen as the every-man House or if they will have a whole new back story.
Either way, Necromunda, if fed new releases often, could very well sky-rocket in popularity.