The need to do without the theatrics in Alien Resurrection, which was basically Buffy in Space. If they do it with Ripley again it should hark back to Alien, Aliens, Alien3 where she was normal. NOT superhuman. As for the Aliens novels, most of them are terrible. TERRIBLE. Canonically, the movies are the only thing that should matter. If they do it right they won't set the 5th movie chronologically (If they do it at all), and should put it somewhere in and around Aliens/Alien3.