A successful cryptocurrent probably has to start by first having a market that is dissatisfied with the available traditional currencies. If that market were to introduce on (with good tech), then it could immediately see the cryptocurrency used for its intended purpose. At that point, if it avoided the attention of speculators (not forever, just long enough for it to get its feet underneath itself) or could discourage those speculators somehow, what happens then?

Is there some other failure mode waiting, or does it take off?