I think one of the big flaws with any discussion of the volume of Bitcoin moving around is the fact that it can be transferred from one address to another where both addresses are owned by the same group or individual.
With a transaction fee of 0.0001 you could create an enormous amount of "transaction volume" on the network with just 1BTC moving from address to address but never leaving the control of a single owner.
One time someone was doing this with 300 BTC. Every block they'd move it to a new address and because of the amount of coins they never paid a fee.
In answer to OP I'd say bitcoin is still undervalued. When 2-3 coins will buy a house plenty will spend them.