You're taking it way too literally.
What I mean is the kind of cooperative and exploratory adventures you can have, the impact you can have on the world. Valheim feels like a kernel of what MMOs were supposed to be about, what kind of adventures were supposed to be possible in living worlds.
I see the future of someone coming along and 'scaling up' something like Valheim to a much larger experience with more depth. I do not see a future for new games in the WoW/FF14 model, like Lithose said, that genre is basically dead.
My apologies if I misunderstood, sincerely. I would say the "Themepark" MMO isn't quite dead [insert Monty Python gag here] but has stagnated to the point no one is building for it anymore because of all the reasons we were rehashing above. Why build for a genre that one company/game owns? It's too long a discussion to post mortem here yet again but EQ was rocking the world with 500k peak players. Today those numbers would be considered a failure for almost any game that couldn't maintain any significant playerbase of at least that over an extended period of time because WoW has broken investors' expectations, and players drift away from over time, potentially to return to WoW.
Maybe we shouldn't be building the next great MMO but trying to seed in smaller companies/games with more niche audiences; what could have been if WoW hadn't broken every competitor for decades and put in this mindset that one had to topple WoW? I say that noting that there are a few other MMOs that are around but the genre is so warped like space around a black hole, I wonder what would have been with a smaller WoW that would have not killed so many of it's competitors? I would have loved to have seen a Warhammer 40K MMO, a Halo MMO, etc.
Also, there would be more it seems, if MMOs were easier to do, I guess, because there were so many poorly made ones. I played and enjoyed so of many of MMOs that came out in the last couple of decades, too. I know I am forgetting a bunch: WAR, was good, first public events, IIRC, Rift was good for a while, Secret World was AMAZING. KOTOR was pretty good (and still is, I hear), I am sure there are others around; LOTRO is another that I played and enjoyed, Eve, there are too many to list; I know the failed ones are. Maybe the expectation of a forever MMO is the culprit here, and WoW's design Blizzards incredible following allowed it sustain itself long past the point others would have faltered even with the financial and technical support they obviously lacked. Damn its been a long 20+ years we have been doing this. GW2 launched in 2012 and ESO launched in 2015. The drought is real. Its been Destiny and Overwatch and MOBAs and FortNite and APEX Legends since then. There are a few reasons for that, as we previous mentioned.
None of that answers the question about why the world ended when Amazon announced they were going to have a cash shop with boosts in it like several other Major MMOs, GW2, ESO, etc. How did the public expect this ongoing, GAAS MMO to be funded without a sub other than a cash shop?