I dont really agree with that assumption. As those millions of customers havent just stopped playing MMO's in the past few years countless mmo's have been sprouting (Rift, TOR, Eve, etc etc) taking away from blizzards customers. I dont believe the industry is dying, far from it actually. I believe the industry is just diversifying and its just awaiting the next big game that can steal everyone away, but so far no company has created it yet.