I have never played WOW or any other MMO, so I might not 'get' what people do for such a long time

or how much Blizzard changes the game with expansions. Eve Online has also continued for a decade now. So, yes there are games that do it. But it will be something new for me, if a game can keep me interested for 10 years.
I started playing WoW in around 2006 and I've been quitting WoW since around 2010

When I think I've exhausted my enjoyment of WoW, of how I understand or interact with the world, they change things up. Sometimes in a minor way, sometimes in a major way. I simply wouldn't play it if it wasn't still compelling and rewarding :smile: But Blizzard have a script for how the WoW world developers, Bungie have indicated that Destiny will be more freeform.
Hmmm....maybe its just a matter of calling it a new game or rejig-ging the existing one ! If they add a new engine, graphical improvements over time and redo the gameplay with an update and still keep calling it Destiny, yes, I think its just a matter of percieving it as a new game or the same game with updates
Think less about material changes that Bungie do and more about the dynamic persistent world they have said they are trying to create. In the Sony E3 event you saw two dudes, scavenger/explorers, drop in independently next to a Russian wall. What if in a months time, following a few more "public events" like the 'Fallen Assault' shown, the focus shifts less on exploration but on fighting the Fallen back. Say the Fallen grab key resource nodes and flying about is a luxary because they lack fuel. What if they're fighting for pure survival. Maybe the human faction just bug out and call that area of Earth a loss, focus their efforts elsewhere. Maybe some players will continue to fight the Fallen, employing guerrilla tactics, other players will head to places where it's more of a stand up fight. Others will go and assist in grabbing resources, or defending them. The thing about a balanced MMOG like WoW is, that each day you can chose to do something different and play a different way. And everything will aid both you, your guild or your faction in some way.
I remember, when I used to have more time, playing a WoW battleground called Alterac Valley. 40 vs 40 players trying to win the game, pushing, defending, sneaking, grabbing resource nodes. A single game could easily go on for 8 hours if both sides were evenly matched and experienced. Every small win was elation, every lose a crushing defeat. The thought of letting this play out on a larger scale, thrills me
If it's everything Bungie promise. Fortunately, they have a good multiplayer pedigree.