Eventually I think there will be some widely accepted, stable and easily transferable cryptocurrencies, but at this point there's no way to say which ones they will be. Lots of people in the nineties could see the value of internet search, so they bought stock in Webcrawler, Hotbot, Lycos and Altavista. Remember those? They all inflated wildly in a bubble as people poured money in, and long after the bubble popped Google emerged as the dominant search engine.
Since stability is an important factor in the long-term value of a currency, the cryptocurrency of the future will be less likely to see the kind of wild speculative swings in price we're seeing today with bitcoin. Just because the supply of bitcoin is limited doesn't mean they will always be valuable. The value of SawbonesCoin spiked from $1 when I invented it last night to $500 right now, but I'll sell you some for the bargain price of just $400 each. You know that's a great deal because tomorrow all the coins will be mined and the value of them will only go up from then on. I take cash or Paypal.