Single player games can be greatly satisfying as well, but they need a story that keeps the player interested. If we could have a game the size of No Man's Sky with a compelling story plus subplots and complex non player characters, such as the first 3 Mass Effect games (best games ever played in my entire life, ME3 lame ending aside), that would make a masterpiece even in single player mode. ME Andromeda apparently tried and mostly failed (I still didn't play it but watched hours of gameplay to get an idea), let's hope the next one will learn from past mistakes. NMS, which I still have to play, looks like to me a great online experience that could become also a killer single player game once enhanced for that purpose. One thing however I don't like much about NMS is the graphics which although truly beautiful artistically speaking, seems to me a bit too cartoonish.

I partially agree. The reason I disagree is that single player games with compelling story, although my favourite, eventually run out of content, even if it's compelling and if the world is open and freeform. But multiplayer games evolve as the player base is what provides the story and dynamics. In many online games there is potentially limitless gameplay and content, the game engine and environment serve only as the playground for players to build from.

An example is GTAV. Where there are lots of structured things to do yet the players constantly make their own meetups, car shows and other shenanigans.

A notable exception could be Minecraft, where you could have your own single player world and so long as you are interested it can keep evolving.

"The reason I disagree is that single player games with compelling story, although my favourite, eventually run out of content, even if it's compelling and if the world is open and freeform"

That is true, and that alone would make the necessary development not economically viable for any game whose life is measured in few years, but what if, along content provided by players, the game creators could insert new environments with NPCs and new stories without ditching the game? In a few years/decades probably AI could also generate characters that develop themselves according to the environment they "grew" into or events happened during their "life". Dreaming too much maybe:)

I am wholeheartedly hoping for that to happen with Fallout76. Permanence gives a lot of the stuff you do in Fallout a bit more purpose. Like crafting good weapons and building a settlement you like. In non permanent versions the story was the main point so you could skip the looting and crafting if you wanted as you didn't really need it. But in a perfect world F76 you have a reason to build worthwhile settlements and gear and collect resources and so on. I have been playing it as if it were a singleplayer game, so although it is multiplayer that doesn't affect my play through that much.