What's the usage of Bitcoin outside the mainstream of the application such as in black market, gambling and pornographic dealing? I think all the applications above can make sure that the hard currency Bitcoin will not die, however, the true value of it should be shown after it stepping into the mainstream of the application.
It's very hard to estimate what all those transactions means. In fact I think it's impossible, it's a mix between trading, speculation, buying of goods and services... all those transactions that get done in person for cash will never have any meaning unless you are part of one of the 2 parties.
As decentralized exchanges start being operative, it will be even harder to track anything.