A rumour popped up around two years ago about Aliens and Alien³ getting 4K treatments done, but since then nothing, I also saw someone recently say this August but I think that's speculative bullshit.
James Cameron's so preoccupied with Avatar that it's not happening anytime soon, and if it did, it's likely you will wish that he hadn't considering the state of Terminator and Judgment Day. David Fincher doesn't care, and Charles de Laurikza holds no power under the Disney umbrella, especially with their track record of home releases.
Someone might eventually upscale Aliens from scratch but considering the film stock it would be mighty easy to make a complete hash of it, or just use the Blu-ray that although pretty for 1080p the DNR applied to it makes upscaling not all that desirable, and it's very blue.
Alien³ comparatively might be a lot of work with warped frames and such and of course painstakingly fixing the compositing, but it had the luxury of not being awful grainy in the first place, so if you went over it carefully a few times with upscaling and a keen eye that would probably do the trick pretty alright.
TL;DR A34K; will likely be the best version of that film by default for a long long long time if Disney's reputation remains unchanged.