Eventually we will hit a point that each hoarder will realize he has a lot of wealth and wants to enjoy it. Just hope it's not all at the same time.
It's not even going to be all at the same time for each individual in most cases. And unless people are dumb they're going to try to dump during periods of influx of demand (I assume these will continue, what do I know though?). This will temper spikes.
It probably won't, but it might. If there was a lack of confidence in the system, or perhaps a panic where people thought "this is the absolute peak, it's going down to 0, better get what I can", you'll see a massive dump. That would only happen if the actual value of the coin was much higher than the perceived value by the hoarders, and they believed that everyone else was figuring it out as well.
This problem is somewhat magnified by the fact that a very few number of people have a significant amount of hoarded coins. This means that there are less decision points on when to sell, and it's easier to get a panic when you only need a few people involved. On the other hand, it means those few people are fairly dedicated and unlikely to panic where a lot of people in a crowd may. It does create a more volatile market since smaller number of individuals act with bigger forces than a lot of little ones, but it just means things might be rockier than normal.