Seems like a silly thing to suggest, but is there ever a chance that Apple could get too big and wealthy?
They could become too dominant in the market, thus be able to very slowly deliver developments to the customer whilst charging a premium price. (Cough - iPad mini 3...)
Competition is a win for the consumer as it drives prices down and innovation up.
Some people on this forum (the "die Samsung, die" mob) would benefit from learning and understanding this fact as well.