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.
The remittance market is a huge industry that can benefit from bitcoin in my opinion. I also think any businesses that are censored by the gov or Paypal or Visa/Mastercard like Megaupload can benefit massively from bitcoin. It's probably their only option that is free from total censorship and that's a great plus in my opinion.