You think wow would be as successful/last 13 years if it had no type of raiding? MMO genre isn't dying because of change, its dying because people don't have the time to commit to MMOs, when you can get more satisfaction with a lot less play time & there is so many great games being released so often, sinking time into 1 game isn't an option for people.
If the games end game was PvP, it would have a playerbase at 100k nowadays, not in the millions.