I'd love to see one more Ripley's adventure. I just don't want them to retcon two good movies in the series (Alien³ and Resurrection have flaws but I like them, Weaver was amazing in both movies) as this would lead to a very bad fan movie, with lazy writing, where story doesn't make any sense and the Alien series would end up in the same place where Terminator movies are today (each movie is a sequel to T2... so bad).
I love Sigourney, she's my favourite actress (mainly because of non-alien roles in Snow Cake, Copycat, Galaxy Quest, Death and the Maiden, A Map of the World, The Girl in the Park, Imaginary Heroes...), she's always very passionate about new projects, so no surprise she endorsed Blomkamp's idea but she also co-produced the 3rd and 4th movie and she must take the responsibility for where the story went.
Alien trilogy and Ripley's story ended perfectly with Alien³. You can still do some kind of alternative version of Resurrection I guess if you need to bring another version of Ripley back but why would you do it when Ripley 8' story can be concluded without stupidly destroying previous chapters.
I say either do it right and respect previous movies or don't do it at all - Ripley died on Fury 161 and Ripley 8 lives somewhere in France - this story ends here.
Don't reboot. That would be so lame. Just write a good story with new original characters. You have entire galaxy to explore in Alien universe, just use a bit of creative imagination.
BTW there is a kind of sequel to Alien series with Ripley and played by Sigourney (OK this isn't quite serious but she's Ripley here, believe or not):
https://youtu.be/s4X8pwE2tok