If real money for transactions was gold and silver, like 50-100 years ago, that would be another issue altogether.
There is NO SUCH THING as "real money". Money is just a medium that makes multi-party exchange easier, and that obtains these parties' belief that it will not become obsolete or redundant when they will want to use it. It could have been cows, gold, water, or paper... It couldn't be meat, or vegetables because these "mediums of exchange" become obsolete after a short while.
The fact the gold was used for centuries was because of its properties - easy to spot, hard to counterfeit, molds well, not too heavy or liquid, and so forth.
But today, it's basically a commodity like any other.
Take Chinese millionaires for example. Most of them [based on a survey] want to "smuggle" some of their wealth outside the country for rainy days. Gold is a bad medium for that. Bitcoin isn't that good either because it leaves a trail. Darkcoin? Now that's a thought...
Whether Darkcoin remains a good 'store of value'? imho it will until some better 'vehicle' makes it less attractive, redundant or obsolete.