Well, Paul, at some point, when the AFFs and whatnot (still paying $950 a signup or whatever they will get to) run out of people to signup, or are not longer able to generate signups, the problem solves itself. Tube sites in particular as they are right now are incredibly sensitive to a loss of sales, because these guys are often taking in $x+25 dollars and day and paying out $X for hosting and such. When that number slips down $50 a day, suddenly they are paying out their pockets to run their sites, and then they die very quickly.
I have noticed a few real tube sites converting into fake tube sites pretty much directly. That means they look like tube sites, but they link to sponsor galleries or directly to sponsor sites. I have seen a few just hotlinking other tube site's content (and doing a bad job of it).
The economics of the deal keeps moving...