Current situation:
Bitcoin it is an exchange collectible thing used exclusively between young male people involved into one or more of: drugs [only because you can't trade with banks anywhere in the world], gambling like poker, betting [only because you can't with US banks and lots ofther places where illegal], video gaming hardware and software [this because geeks "mine" with the need of ultimate graphic cards, "litecoin" exists because with bitcoin you can no more mine with video gaming cards, need ASICs], ddos/virus service, and hosting or service capable of resist ddos/virus [eventually same guys provide both, in a circle]. But really, 99% of transactions are not done to buy drugs, gamble, videogaming hardware or hosting or any product: that's simply trading for forex-like investment game. There is no any other audience for cryptocurrencies at the moment, for what I can see. Is not even for the fact that someone is afraid it is illegal.
The future:
In the case (unlikely?) that all of the torrent and filelocker sites (including forums with links to them) will lose all of: billers and advertising sources (both, not just one of the two!) - then these would end up to be much like drug shops and so, would actually need to use bitcoin, as last resort. However, as AdultKing knows, even thepiratebay and filelocker forums main sponsors include respected cam program(s) actively promoted by most GFY users, also in posts and signatures. Plus gambling and various make money scam videos and toolbar spammy installs and whoever got the cash to pay advertising space there. Until now, those piracy sites can have their hosting and legal protection fees paid (plus a profit) by a large number of advertisers, even competing for the space and keeping the price up. I know, since I run a cam site, and I find always the piracy sites answering me, that I can't advertise since cam program X or Y pre-paid for month(s) in advance... but to try after a few months, just in case. Piracy sites they're more expensive and full-booked than legal sites to advertise into, try yourself
About adult sites:
I may add bitcoin + litecoin revshare program in a few months (when free time of developer permits), just to see if some people who is enthusiast of bitcoin and litecoin may want to support my site, just for the fact I supported bitcoin + litecoin. You see like fetishits guy here he posts bitcoin supporter sites for free with no affiliate link, this is useful. I would make a few friends who may post my site link around, that's what I expect - nothing more. Then in 2020 perhaps I am ready, when it starts to go more mainstream - or if will keep vapourware in 2020 - I wasted some time in adding this feature, just for hobby. I wasted way more time and money paying PPS to filipino chat traffic affiliates