There'll need to be a lot more mass adoption for scarcity to cause the price to increase, significantly.

Instead of a near 20 million coins, the Bitcoin protocol could have called for a mere 1 million coins, or 2 million coins (number doesn't matter) to be mined over a set time. Supply and demand would predicate the price to be higher by virtue of there being less available coins. So while there might not be enough full coins to go around, that doesn't play into scarcity unless the demand shifts up. For that to happen, I'm thinking there'd need to be a few large currency fails in order to cause mass adoption, and we're a bit far from that as of today.