Some of these old MMORPGs came out over twenty years ago now, but are still available to play even if they're just in maintenance mode.
However, if an MMORPG is popular or well-built enough, it may withstand the test of time. All the hours, effort, and money players have invested into the game seem to go to waste, and all of those great quests and missions, along with the compelling and detailed lore, are lost forever. It's disheartening when a favorite MMORPG goes offline, and not just for the developers or investors.