Considering that I work at a Toys R Us, and often work in the Boys/Girls and Lego section.. I see a lot of Lego merchandise out there and the customers who buy it. While Lego is indeed intended for children, there are some older folks who are into Lego as a hobby. Many of them are adults who are buying Lego's of licensed franchises from Ghostbusters, Star Wars, Avengers, Justice League, Back to the Future, etc..
So while this is likely never to happen, though I am sure that there are some figure customizers out there who have made such... How would the fandom feel if Lego had actually got the license? I mean we've already got an Alien children's book on the way out, so what harm could a Lego AVP really do aside get some cynical fans grumbling?
How would you the fans feel if Lego had decided to span the entire franchises from the Alien, Predator, AVP and even Prometheus films to do their own thing? Even using characters that would clash in main continuity like Charles Bishop Weyland and Peter Weyland for things like AVP Lego games or incorporate it into their Lego Dimensions?
So before any cynics out there yell at me for entertaining the idea.. this is all hypothetical and likely never to happen.
