Back to the OT...
I think while we could have had a Alien 5 take place on the Sulaco where then Ripley loses her Memory a bit because she gets Face Hugged, and Newt and Hicks Die... may sound like a work around....
There really is a Short Window of Time that a Movie would take Place in, and also being set just on the Sulaco could be limiting..
HOWEVER....
Blomkamp had some Interesting Ideas with his Alien 5 Project and Originally it never had Ripley, Newt or Hicks in it.
And so i think that a Blomkamps Alien 5 Idea could still work and should be looked at again, but as a Sequel to Alien 3 that is set some Time After, be it 5 years, 10 years, or 25 years...
We could get a Alien 5 and 6 if you would that would be set before Alien Resurrection where the Conclusion would show us WHY the Company would not get its hands on the Xenomorph until Hundreds of Years latter with USM and the Cloning of Ripley.
So the IDEA could work..... only they would have to DROP the Old Gang... (Ripley, Newt and Hicks).
They could instead introduce Amanda Ripley.... have it that she has been in Cryo-Sleep for Many Years, and that the Photo that was shown to Ripley in Aliens was a FAKE as the Company Covered Up what Amanda Ripley had really been up to (her time with Alien Isolation and any Follow On Stories).
Upon Discovery of Amanda... she could be informed the Xenomorph threat is GONE with the Destruction of Hadleys Hope... but she could then inform those who recovery her that the Xenomorph threat would NOT be Eradicated by the Destruction of Hadleys Hope and that the Entire Planet (or another that has Eggs) would have to be Destroyed..
This Information could then be used by a Company who then Obtain the Derelict or another such Ship...
The Plot then Unfolds like what ever Plans that Blomkamp had, but we replace Ellen Ripley with Amanda Ripley and replace Hicks with another Male Protagonist.