I don't see why it couldn't reach $10,000 some day and I wouldn't be surprised if it happened in the near future.  Personally, I was surprised when the exchange rate stayed pretty stagnant hovering around $130 for quite a long time while the difficulty was skyrocketing.  Theoretically, I would think that as it becomes more difficult for people to mine bitcoins that as long as the demand for them stays high then the value of them should also rise.