The Grey Album's next step problem

Tyler Cowen here links to this article discussing the "Grey Album," a mixture of The Beatles' White Album and Jay-Z's Black Album. The "best argument against" this type of mixing:

""A one-off, isolated thing like 'The Grey Album,' yeah, it's interesting," Carter says. "But I think we're going to be getting a lot of it. You're going to get 'The Dark Side of the Moon' album put together with this, 'Sandinista' with Bob Marley. It's gonna be crazy. I think it's gonna get out of control.""

I think that stops one step short of providing a satisfying answer. After all, there's nothing inherently wrong with things getting "out of control" -- what does that even mean? And why would it be bad? I think the potential problems are two: First, those who have a strong aversion to the manipulation of their music--those with a strong desire a type of moral right over their work--will not release music. At least on the margin, this may influence some behavior. It doesn't strike me that a lot of musicians will change their behavior however, and even so, mixing arguably increases demand and may spur other musicians to create more. So that strikes me as more of an empirical question, and not something we can answer in the abstract.

Second, an argument put forth by Landes and Posner is that we want to give broad derivative control over copyrighted works so that authors don't sit on their works. In the cleanest case, this means that we want George Lucas to release Star Wars: A New Hope, and then later go back and do Empire Strikes Back and Return of the Jedi. But if Lucas doesn't have control over derivative works, and he suspects the first movie will be a hit, he may sit on it for several years while he makes the sequels. Thus, if things really get "out of control," some musicians may hold their works back -- that is, Jay-Z doesn't release the Black Album until he's finished mixing the Grey Album. Everyone loses when we wait longer for the things we want.

Even this argument, while somewhat stronger, isn't an airtight case. I'm not really sure, realistically, what the danger is. It seems unlikely to me that the vast majority of artists will stop producing music either because they are offended by the use of their works, or because the return to producing is lower (and, as I mentioned above, there are countervailing forces at work as well). The best argument is still that this creates an incentive to sit on the works -- Jay-Z will release the Black and Grey Albums together, to satisfy demand in both markets. Even so, how big an effect can this be, and how often will it crop up?