Despite Godzilla vs. Kong’s ending, Kong didn’t truly earn his “King” title in the movie. Ever since his first movie, the MonsterVerse has avoided his “King Kong” name, presumably because of rights issues. However, the events of Godzilla vs. Kong seemingly handed it to him, but without outright addressing the change.
Kong’s unspoken evolution into King Kong happened in the Hollow Earth portion of the story. Accompanied by humans associated with APEX and Monarch, Kong found an ancient temple once occupied by his ancestors, who lived in the Hollow Earth prior to the relocation to Skull Island. A symbolic moment occurred when Kong picked up the ax made from Godzilla’s dorsal fins and sat down on his ancestors’ throne. As confirmed by Godzilla vs. Kong director Adam Wingard in the commentary on the Blu-ray release, this scene was meant to show that Kong has finally acquired his “royal status”. Kong roaring atop a cliff in the final scene was another sign of the Titan asserting himself as the new king of the Hollow Earth.
While moving to the Hollow Earth was a major step in Kong’s journey, saying he’s now “King Kong” or the alpha of this place may be premature. After all, there’s no proof as of yet Kong is the apex predator of this corner of the MonsterVerse. Kong and the humans haven’t spent enough time there to understand the threats that exist in this newly discovered ecosystem. There’s no telling what Titans live in this strange, unfamiliar world. It could be the residence of all sorts of powerful monsters who might be considered rivals to Kong.
For this reason, Kong may not have a rightful claim to the title of “King of the Hollow Earth” just yet. Kong can’t just assume this mantle without unseating the current alpha (if there is one). Kong is being hailed the king regardless of the fact he did very little to gain this position. Beating Mechagodzilla when Godzilla couldn’t was impressive, but it has nothing to do with his reputation in the Hollow Earth. Kong needs to do more than just sit on an abandoned throne before he can truly be called “King Kong”.
A sequel that continues Kong’s story from Godzilla vs. Kong can rectify this and give the ape a chance to really prove himself in the same way Gojira did in Godzilla: King of the Monsters. To become the alpha, Godzilla had to dethrone and kill Ghidorah. Kong can pull off something similar in Kong 2 if he receives a challenge from the Hollow Earth’s real king, which could turn out to be Toho’s King Caesar, or perhaps an original Titan. Kong getting a victory over this opponent could cement his status as the Hollow Earth’s “King Kong” in Legendary’s MonsterVerse.