Not producing new content will clear the game of all PvE players, and the PvP isn't good enough to keep it alive after. The game would turn into 100k player ghost town like all the MMOs of yesteryears are now.
EverQuest is 15 years old now and expansion #20 comes out this year so it's pretty safe bet that WoW which was 25 times more popular game than EQ will be up after 15 years too, most likely much much longer.