The next film in the series will be a Forbidden Planet
remake with the engineers being the Krell and Robbie replaced with Robert, another android.
One thing I thought of, who's to say the Engineers don't eventually succeed in their plans to bomb Earth with the goop? We never visit future Earth itself in the ALIEN movies (ALIENS is on a space station), it's referred to as a "shit hole" in Alien Resurrection. According to General Perez, the xenos were needed for "Urban Pacification". Maybe Earth is full of killer mutants?
It's just common knowledge so no one says it outright in the films. Like the Stormtroopers being clones in the Star Wars universe.