As much as a mess as GTA Online is, playing it and Watch Dogs multiplayer has convinced me all MMOs have been obsoleted, Guild Wars 2 included. We’re just seeing a lag before reality catches up with developers /players.
In every case, you have an engine built to accommodate hundreds of players in a phase/instance. And the level of interaction is much weaker because of the technical limitations. Then you play Watch Dogs in multiplayer and go “wait, do I ever interact with those 100 other players in that MMO I was playing?”. And you don’t, you just play a single player game in a weaker engine, and then play PVE/PVP in an instance with 16-32 players.
And how many people do the GTA and Watch Dogs engines accommodate? About 16-32. With much better gameplay. I.E. better combat than “lock on and play piano with the number keys”. Better game design than “do this boss fight perfectly, or everyone dies and you start all over”.