If we take the MMO genre at face value, it's fairly easy to argue that even Grand Theft Auto V fits the bill. It is a massively multiplayer online game, and even could be argued to feature RPG elements as you build your character, equip them with fancier clothes, guns, and cars and build up your estate with nice apartments and bigger mansions.
However, Grand Theft Auto VI could take this even further. Rich Vogel, an MMO veteran who has worked on Ultima Online, Star Wars: The Old Republic, Halo Infinite, New World, and more, revealed he's heard the game will have typical MMORPG features at launch.
"If what I have been hearing about GTA 6's features and gameplay is true, it could evolve into an MMORPG, as many of its planned features are typically found in MMORPGs," he told Wccftech in a recent interview.
It's worth noting that Vogel didn't work on Grand Theft Auto VI, and that therefore this is just second-hand information or a rumour, in other words. That said, considering that Rockstar has always pumped a lot of money and effort into its online mode since the launch of Grand Theft Auto V, we'd expect no less in the sequel.