[aneth4]

Nobody who owns bitcoin gives a damn who buys what with it, any more than you care who buys what with your country's currency. It's currency.

What could threaten bitcoin is a major flaw in its algorithm, which seems unlikely in the near future, and the hacking of the primary exchange - MTGox. In fact, I keep my Bitcoin at MTGox with the knowledge that if they lose my Bitcoin, the value will plumet to nearly nothing regardless of whether my coins are there or not.