Democratisation of the medium = less profit
In the growth days of the internet, every bloke with a camcorder became a low-rent porn producer, producing thousands of hours of poorly lit, shot, audio video and starting up sites. Monetisation failed for whatever reason, and this dumped a huge amount of 'free porn' on the market as these sites shuddered their death rattles. A few aggregators were in the right place, most became sub-brands of the big few.
They have the challenge of getting people to pay for something that is now free, they can't rely on dodgy dialers any more, all the streams that made Sullivan and Gold rich enough to buy West Ham are gone, Fawn (Raymond's granddaughter) has a property portfolio covering most of Soho, but I very much doubt she'll be doing much publishing.
The ubiquity of instant, free films means there may still be money right at the boundaries - where there are still questions of taste or legality - as the rich middle easy ground has gone. A fondness for 'particular presenters' will help to a degree, but if I can see the wobbly bits of Hollywood starlets whilst on a train, it's not a massive deal. And males seem to be hard programmed to collect diverse sets as opposed to remaining faithful to one selection of pixels, so I'm unsure that'll work except for boundary cases anyway, and then be incredibly time-sensitive as their pertness sags.
Biting the hand that feeds IT
