I like to imagine, “live service” is a buzzword so investors think that the game will constantly make money. After seeing how hard the Avengers game flopped I’m surprised they would announce this.
A game that receives updates in a regular manner. There is an expectation that players support these updates by buying things, and to encourage this live service games tend to have things that try to be habit-forming or are available for limited periods of time, such as battlepasses.
Destiny 2 is a live service game. Many of the voice actors in the game are employed to narrate lines as game expansions are released (dlc) over several years