Aliens sequel is a bad idea, mainly because I really like Alien 3 and I'm certain his sequel wouldn't be as good and would mess up the franchise even further. The prequels are what they are, at least the original series timeline is intact, let it stay that way.
But let Blomkam do the next AvP movie, set in the future and Aliens technology. A film version of AvP 1999, yes please!