Even though small periods of increased revenue are possible, the overall line for adult points downward. Anyone who pretends otherwise refuses to deal with reality.
Porn is now an essentially free product. There are so many tubes with different content that for most parts of adult even the most demanding addict can get his fix for free. Only a few small and specific niches are an exception to that.
Moreover, each year a larger percentage of adult men will have grown up with the internet, and will thus be more knowledgeable of ways to get porn for free. We now have people in their twenties who can't even remember not having an internet connection. Ten years from now, the same will go for men in their thirties. And make no mistake: a better knowledge of the internet translates directly into a better knowledge of ways to get free porn.
Take a look at this:
http://www.ovguide.com/adult-visits-alltime.html
Now ask yourself: how many men need more porn than they can get there for free? And how many men discover those sites every day?
The idea that things will get better is a fantasy. Ratios will keep dropping.
Of course, consolidation will still benefit some in this industry, and others will continue to dominate specific niches and be less affected than the mainstream. Aside from that, making a decent living as a small-scale entrepreneur in adult might be harder than it used to be, but it's still quite possible. So the industry does have a future - albeit one that isn't too bright for many.