Don't invest in content that can be played into the game's lifespan, creating an array of ever more interesting ways to challenge your players new and old. All that matters is 'NEW CONTENT'! Let the old content DIE and the resources used to make it burn on the endless fires of the gear treadmill!!
Everyone? This is how you take the MMO genre's promise of an indefinitely profitable game, and ram it into the ground in less than the decade S-E are already considering an optimistic lifespan goal.