Some of them are already doing it so that is goods, more will follow anytime soon for sure, just a matter of time.
Even here in forum i had notice one signature campaign which is relevant for porn sites. Even you could find the sites which accepts you as a premium member with the bitcoin payment. Just google it you can find many.
So you are talking about xotiva.tv? Yes there are a lot of porn sites who have been doing that because they can see that their customers will prefer to use bitcoin because of its anonymity. And also there are individuals here that are promoting pornography as it is their username here in forum, I saw some but I can't remember their names.