It's unlikely and almost inconceivable to get to $5, though, because the main benefit of having a large, distributed network is that it takes a sizable amount of people to sell out to drop the value. This is inertia of a stock. You can better believe for the number of people panicking and selling off there will be an equal or greater number of people holding on to it, and that's why I can only see it dropping 50%, maybe 75% at max, in true market free-fall conditions.
I believe drop to $5.00 could only happen if anti-bitcoins laws are approved because of fear of laundering money. Bitcoin would still be used but there would be almost no demand and extensive supply thats why such low USD/BTC