In Alien, the drone was turning Brett (Dallas is debatable) into an egg, to complete its life cycle. With the introduction of a Queen, it can be deduced that, in the absence of one drones will make eggs themselves until a Queen hugger appears one way or another.
That's what I'd like to see in the movie if the Queen's not there from the get-go. No molting, no Praetorians, just a drone making an egg with a Queen hugger inside.