Which brings us to an interesting question... how long does something have to go before we consider it a success even if it fails later? When something comes along to defeat Facebook, are we going to call Facebook a failure? Was Myspace a failure?[1] The fact that Bitcoin has ran this long, given some huge payouts and legit(albeit small) businesses accept it as payment, I'm almost ready to call bitcoin a success even if it fails 6 months from now.
And if/when it fails, Bitcoin can reasonably claim to have shown that distributed computer-based currencies are feasible and people will use them. Even if a successor comes along and solves Bitcoin's problems, you could justifiably say that it only succeeded because of Bitcoin.
Telegraph... colossal fail. But note that the first wire transfers in 1871 were done on western union's telegraph system. Yours is an interesting question. The tulip mania bubble people like to reference was less than a year long, so BTC is already beating that.
1. http://www.theguardian.com/technology/2006/aug/13/observerre... Myspace listed among the top 15 most influential sites.