I've read that Bєℓ Aмι website for example has close to 1 million members a year. Now if you make a simple calculation: The majority of the members probably are 30-day members who pay 30 Euros a month. So that makes 30 million euros a year (36 million dollars!) if nobody would extend his account so the number is probably quite higher because lots of members often extend their accounts - so we can say the amount of money is at least
40 million dollars per year if not higher - and this is what they earn only from memberships - if we don't even mention DVD sale.
DVD sale is still quite high I'd say. Existence of hundreds of DVD selling websites is a witness of that. Majority of people still are "traditional" DVD buyers. Our kind of file sharing is still considered as significantly small. Music companies are at the greater danger here because music files are quite small and easy to share, that's why music companies are much more aggressive in their fight against file sharing.
On the other hand many gay porn companies even gain from file sharing, because it is kind of commercial for them. This way they become more known and many people (including me) have decided to become members of certain websites after downloading some of their vids from other sources.
So I don't believe porn companies will ceased to exist because of file sharing. Well the world crisis affects every one, even porn world. But porn will survive
They will just have to become better, more interesting, more creative.