I think you guys are getting hyped up over a misinterpretation. Don't be surprised when its confirmed that Blomkamp's film will be set after Resurrection.
It could go either way. Sigourney's talked a lot about finishing Ripley's story after Resurrection, so I wouldn't be surprised if Blomkamp re-wrote to accommodate that. But it's not impossible that a retcon of sorts could happen. Personally, I think "genetic siblings" is more referring to tone, style, aesthetics, etc. But still, it's all very vague at the moment.
Boy, I certainly effin' hope we are right about the misinterpretation. Because I've never been this disappointed with a film announcement in my life.
That the ALIEN series didn't do things like this is why I had so much pride in being a fan for so long. I forgave the AVP stuff because it was so sub-par in contrast to the others, that it felt like no-one would take them seriously. But say what you want about A3 and A:R, what they have in common with the ALIEN series is that they are aesthetically serious films, each with its own very distinct themes that all build upon the others. Even Prometheus. Hick's was cool but not cool enough to retcon two entire films and take a dump on a series that maintained it's storytelling integrity for this long.
I will also call it now: If this gets retconned, what you will end up with is fans endlessly shredding apart what aspects of the mythology no longer make sense, like the star wars prequels. Mark my words, those two films added an infinite amount to the series that many fans of a retcon aren't even aware that they are applauding be ignored, and when it's done, it will have opened a giant can of worms that won't be able to be undone.
To those saying how great this sounds, well how great did all the same people think Prometheus sounded until they saw it? What about A:CM? Remember how excited everyone was when they heard Hicks was back? I like Prometheus, I would hate it if it trashed the continuity. I even don't mind the Hicks elements in A:CM, but the game sucked. And the odds are thats the same can of worms doing something like this will be. Retcons of any kind, or any new information that changes what people already knew/learned or accepted previously, just makes a big mess out of things. Continuity is one of the most important facets of storytelling. Messing with it is always, always a bad idea.
I will also suggest, that all attempts to make sequels after A3 have failed precisely because they tried to make things more like Aliens.
Doesn't anyone else find it hard to take the new Terminator trailer's seriously because of the retconing?