Those saying BTC has no inherent value (as opposed to gold, for example) are completely overlooking the fact that BTC is the only kind of exchange that can be used for illicit activities in a relatively untraceable manner (good luck buying stuff on SR using gold).
Unfortunately, BTC is traceable if governments decide to spend the resources monitoring transactions, and I suspect this would be the primary motivator in the demise of BTC and a replacement with a more anonymous currency - the other motivator being that there's a huge financial upside for being an inventor or early adopter of a successful cryptocurrency, as BTC shown us.