Its all about control, Disney take more percentage from theaters then any other studio and they want everybody to use there streaming service, they got it all Avatar, Pirates, Marvel and I'm sure they'll pull all the Blu-rays, DVD's and UHD 4k Blu rays in the next few years.
They don't give a dam about ether Predator or Alien, they are not box office sensations and selling them for what fifty million ? That's pocket change for Disney and it could create some competition at the theaters, they want to dominate the theater chains.
Lets just go out and enjoy The Predator on the big screen because everything that has a beginning has a end.