In addition to the 2015 agreement hashed out with Sony for Spider-Man, Disney's purchase of Fox in 2019 gave Marvel Studios access to the Fantastic Four and the X-Men properties. 

In late 2020, a Fantastic Four reboot in MCU was announced with Spider-Man: Homecoming trilogy director Jon Watts helming the production.  

The arrival of the Fantastic Four in the MCU also poses new challenges regarding how they will be integrated into Phase 4 or 5's story. 

In Marvel comics canon, the Negative Zone is a parallel universe formed by antimatter in which the laws of physics do not fully apply.  

In one of his many searches to learn more about his universe and others, Reed Richards discovered the Negative Zone.  

the events of Civil War. In the Earth's Mightiest Heroes animated series, something similar happened, except on a larger scale, with Prison 42 used to detain the most dangerous villains of the show. 

In Marvel's Ultimate universe, the Negative Zone was called the N-Zone and was the subject of Reed's study from a very young age.  

The MCU could take inspiration from the Ultimate universe, as it did for many elements in Phase 1, to explain how the Fantastic Four got their powers.