I think you will see a whole big range of 'meme-coins' develop, as JesusCoin, LibertyCoin, Americoin, AfroCoin, EnviroCoin, things like those, get produced and minted... people will tend to want to deal with their own kind... and then there will be metacurriencies:  Bundles of currencies to suit each individual.

At any rate, it is impossible that BTC will be successful and others not, though I would bet that BTC holds the lead.  But there will be a whole 'ecology' of coinage out there... each coin with its own niche.