To all of the people saying it's lazy and throwing the word "fanboy" around (as if they aren't being childishly fanboyish of A3 & A:R themselves):
Resurrection was the laziest shit I've ever seen. Going to such lengths to bring back Ripley it was essentially a comedy. And Weyland-Yutani being bought out by Wal-Mart? They really didn't give a damn when they were writing that script. A retcon/alternate continuity opens the door to leave that bullshit behind, and most fans (and yes, I say MOST), are happy to take that road than suffer Resurrection (which was, again, a lazy film that brought back a character that should have stayed dead in a lazy, contrived manner). And even Alien 3 was lazy as they STILL haven't explained how that damn egg got where it was (even the piss-poor A:CM DLC danced around the issue).
An alternate continuity is a brave thing to do. It's a high risk - high reward scenario. It's what many fans have been wanting for years. If it flops, it'll be miserable, and Blomkamp will be hated by much of the Alien fandom (if not all of it) forever. If he succeeds, this franchise is back on-track as being strong, rather than being on life support.
There's a lot riding on this movie. It ain't lazy. He's got a LOT to live up to. I don't envy his position.