The shapeshifting Skrulls were a race of aliens that first appeared in the MCU via Captain Marvel. Ever since their introduction, comic fans were expecting an adaptation of Secret Invasion would follow. This seemed to be likely when Spider-Man: Far From Home ended with the twist that the Nick Fury and Maria Hill that Peter Parker had been working with were actually Skrulls in disguise. It established a concept integral to the Secret Invasion storyline in the comics: anyone could secretly be a Skrull. A Marvel TV series in which any superhero or even villain could be a shapeshifting imposter is an intriguing concept and a set-up for a series filled with twists and turns.
No release date has been set, but the announcement confirmed that the series would bring back Samuel L. Jackson as Nick Fury.