Guardians of the Galaxy Vol. 3 will conclude the stories of the original Guardians, and it might be the Fantastic Four who will replace the Guardians of the Galaxy in Avengers: The Kang Dynasty. Curiously, if Marvel Studios had the rights to the X-Men and The Fantastic Four from the start, then perhaps Guardians of the Galaxy would have never happened, at least not so early in the MCU. Far less known among the general audiences than the Fantastic Four, the Guardians of the Galaxy were one of the MCU’s biggest surprise successes, and it will not be easy to replace them going forward.
Guardians of the Galaxy (2014) proved how far the MCU had gone, as even a less popular Marvel superhero team was able to launch a successful franchise within the Marvel Cinematic Universe. Now, two Guardians of the Galaxy films and two crossovers with the Avengers later, the Guardians are heading to their final adventure in Guardians of the Galaxy Vol. 3. Considering that Avengers: The Kang Dynasty and Avengers: Secret Wars will release after Guardians of the Galaxy Vol. 3, the Guardians are not confirmed to be in the next Avengers movie. In fact, it would be no surprise if most of the Guardians are not in The Kang Dynasty. However, Marvel will introduce a new superhero family right before Avengers 5, the Fantastic Four.