Warning: SPOILERS for Godzilla vs Kong.
The Godzilla vs. Kong ending properly solved the MonsterVerse’s alpha Titan problem. The marketing for the crossover indicated that having two alpha Titans on the same planet wasn’t going to work. Godzilla: King of the Monsters ended by having Godzilla unseat Ghidorah and take his place as the alpha. Rodan and several others recognized his rise, but one Titan in particular – Kong – didn’t regard Godzilla as his new alpha.
Kong electing not to follow in the footsteps of Rodan, Behemoth, Scylla, Methuselah, and the third MUTO was foreshadowed by his actions in the King of the Monsters novelization. It was said that Kong didn’t answer Ghidorah’s call because he didn’t consider Monster Zero to be the alpha. If Kong wasn’t willing to accept him as the King of the Monsters, it stood to reason that he wouldn’t do so with Godzilla either. This was reinforced by trailers and promos for Godzilla vs. Kong, which labeled the King of Skull Island as another alpha Titan in the MonsterVerse. And as expected, all of this turned out to be true. Though Kong seemed to be well aware of how dangerous Godzilla was, he didn’t hesitate to match blows with him.
Kong’s potential to be the alpha of the Titans was a major factor that contributed to their war with each other. It was stated in trailers that the conflict couldn’t end until one of them submitted, and that it wasn’t possible for there to be two alpha Titans in the MonsterVerse. This increased speculation over how Godzilla vs. Kong would allow them to co-exist, as it would have been out-of-character for either Titan to bow down to the other. Ultimately, the movie found a suitable way of making it work. After beating Kong, Godzilla spared his life, since asserting his dominance and letting Kong know that he was the true alpha was Godzilla’s main goal in the first place.
Kong letting go of the axe when faced with the option of fighting Godzilla a third time showed that he wasn’t going to challenge Godzilla’s claim to the crown. But, the MonsterVerse isn’t making Kong a minion of Godzilla like it did with Rodan and King of the Monsters’ original Titans, and that’s for the best. Instead, it sent him down to the Hollow Earth, which contains the throne of his ancestors. In the movie’s final scene, he was shown running around his new home and beating his chest. What all this means is that Kong has become the “king” of Hollow Earth. By taking this title, Kong has achieved a role that has made it possible for both him and Godzilla to share the same planet.
Its unlikely that Godzilla will feel threatened by Kong by in the future, or vice versa. He’s the alpha of the surface, whereas Kong is now the alpha of the Hollow Earth. The two can now remain in separate worlds, without either one interfering in the activities of the other. This works out for both creatures, as Kong making the Hollow Earth his new domain proves that the MonsterVerse can indeed have two alpha Titans.