The biggest reason porn is in decline is because practically EVERYONE is a porn star nowdays. girls sit in front of a webcam and strip. Who the he11 needs the porn industry when this is going on?
sh1t, if you wanna see it in person, just go to a biker bar and watch a couple drunk chicks lez out.
An uptight populace is a prerequisite for a porn industry to thrive. When the populace loses it's hangups about sex and nudity, there's no point to porn...at least not any porn that you pay for. There's no longer a captive audience.
The only way for the porn industry to remain valid is for it to morph into something of sufficient debauchery such that it is not permitted out in the open in mainstream society. But there's a catch. Even debauchery reaches a point of diminishing returns. There's a fine line between enticement and intrigue...and disgust, revulsion.