If BTC continues the upward trend with the level of volatility we are used to then as you say, more and more people will learn to just hold until we get close to a stage where very few btc are actually traded relative to the total supply. This will only lead to more upward pressure until a price is reached where people are content to dump.
I guess its a very long term investment if ever people would really wait that total supply. And we cant predict how other people would think and use bitcoin. Some may take advantage and others may just be traders.