If Bitcoin is to be considered to be gold, then I would argue that Namecoin should be considered as Platinum. Not silver or copper, but the rarest of precious metals, platinum.
Let’s look as some pertinent numbers to bolster the argument. Bitcoin has in circulation a total of 12 millon coins in circulation and with a current difficulty of 609 million. By contrast, Namecoin has in circulation a total of 7.4 million coins with a current mining difficulty of 456 million. In other words, there are nearly twice as many bitcoins as namecoins, furthermore, the it requires on 50% more effort to find a bitcoin than a namecoin.
In terms of scarcity, Namecoin indeed is like the scarcest of coins. Platinum is an extremely rare precious metal, only 6% of platinum is mined as compared to gold. Given how rare platinum is, it is surprising that the price per ounce of platinum is not comparatively more than gold. Platinum is currently at $1,358 per ounce while gold is at $1,240 per ounce. Clearly Platinum appears to be under valued compared to gold if one considers scarcity.
Namecoin compared to Bitcoin is also considerably undervalued. As of this writing, Bitcoin is trading (quotes from BTC-E) at $946 while Namecoin is at 11. This is an extreme disparity, which I believe over time will be corrected. In fact, it may not even be ridiculous to find that the price of Namecoin exceeding the extremely lofty levels of Bitcoin!
There however is more to a crypto-currency than scarcity. Another important consideration is the liquidity of a coin. If a coin is heavily traded like Bitcoin is across multiple exchanges around the world, then the value is proportionally increased as the trading volume increases. This kind of network effect allows even larger sums of money to be transferred via Bitcoin without substantially affecting the price.
Namecoin is not traded in as many exchanges as Bitcoin. For a long time, the volume for Namecoin at the BTC-E exchange was quite anemic. However, in the last few days, the volume in the NMC/USD trade exceeded 23 million USD a day. This is a remarkable change and bodes well for the future of the coin.