Not sure that more of an ending is needed.
But I have been curious to see a continuation, so I ordered the Original Sin novel, which is apparently the only novel that's ever continued Ripley 8's story. (I hear it includes a pre-Prometheus depiction of engineers though, so it probably won't fit into the canon anymore.)
As for a film depiction, the older Sigourney gets, the less I want to see her play this new, animalistic, sexualized version of Ripley...