Marvel Studios sees Julia Louis-Dreyfus' Valentina as the Marvel Cinematic Universe's Nick Fury replacement. Samuel L. Jackson became a foundational piece of the MCU when he debuted as Nick Fury in Iron Man's post-credits scene. The shared universe is now in the process of introducing a new batch of characters after Avengers: Endgame, though, since the movie put an end to the original Avengers roster. Marvel Studios has quickly done this by introducing direct replacements for certain characters, including having Falcon's future as Captain America signaled in Avengers: Endgame's ending.
The exploration of Sam Wilson taking up the Captain America mantle came in The Falcon and the Winter Soldier. The Disney+ series teamed him up with Bucky Barnes to explore the history of Captain America and what the stars and stripes really stand for. The Falcon and the Winter Soldier was able to introduce a number of great new characters in the process, such as Isaiah Bradley and John Walker. The show also included the surprise debut of Julia Louis-Dreyfus as Contessa Valentina Allegra de la Fontaine, who recruited Walker to join her secret team and become US Agent.
Louis-Dreyfus' debut as Valentina in The Falcon and the Winter Soldier and return in Black Widow led to many questions about her role in the MCU's future. There has been a lot of speculation about her forming the Thunderbolts or Dark Avengers, positioning her as almost an evil Nick Fury. It seems these comparisons are quite accurate, as even Marvel Studios thinks of her character in this fashion. In a quote in Marvel’s The Falcon and the Winter Soldier: The Art of the Series (via The Direct), producer Nate Moore said Louis-Dreyfus is the MCU's Nick Fury replacement.
The Countess Valentina Allegra de Fontaine is a character that has a rich publication history… and to some degree, figuring out who can fill those shoes, which in our mind is in a way taking the reins from Nick Fury, was tough. But when we thought of Julia Louis-Dreyfus, there was a fun energy to her that immediately you realize this person has a weight and a gravity, but they're not the same as Nick Fury. It's a completely different energy.
Replacing the original Avengers members is a clear focus for Marvel Studios in Phase 4. The combination of Ironheart and War Machine will help replace Iron Man, while Falcon is directly continuing the Captain America mantle. Clint Barton is not the only Hawkeye anymore after introducing Kate Bishop, and Black Widow brought Yelena Belova into the MCU to replace Natasha Romanoff. It will not be long before She-Hulk possibly replaces Hulk, while Jane Foster's Mighty Thor could also replace the original god of thunder. Now, Valentina can be counted as part of this process since Louis-Dreyfus' character is thought of as a Nick Fury replacement.
These comments from Moore also signal just how big of a role Valentina will have in the MCU moving forward. She's already made two appearances in Phase 4, but there is an expectation that Louis-Dreyfus will be in several other projects. If she is a Nick Fury replacement, it also provides more evidence that Valentina is indeed assembling a more evil version of the Avengers. With Marvel recently finding a director for a Thunderbolts movie, that will likely be where Valentina's MCU efforts culminate, much like how Fury's superhero assembling led to The Avengers.
Source: The Direct
