Is there a reason to think this will be a high-revenue use case?
Most cinema is about careful, fine-grained control of the viewer's attention, so I think porn has all of the same challenges that movies do. It's just not clear those will translate to a medium where the user has POV control. But I think VR has it worse in a few ways.
One, people just don't consume that much porn. I know people who will spend 20-40 hours a week playing video games, so $500-1000 on hardware is not an unreasonable spend. But for porn?
Two, previous technologies that have benefited from porn have also increased access. VCRs, DVDs, and home computers made it easier for people to get both a larger volume of porn and access to material suited to their specific tastes. Each has also reduced cost of distribution. VR, though, has to compete with the Internet's existing cornucopia of free and low-cost porn. VR will always have a much smaller and more expensive selection.
Three, a bunch of VR distribution will be tightly controlled. You can bet that Sony's not going to be selling any porn, for example. We live in the age of app stores, so I expect a variety of entities to try to control VR distribution channels. If they succeed, it may make VR porn a very small market.
I know this is bandied about a lot, but I imagine you'd hit uncanny valley pretty damn fast in a way that's difficult to overcome. I'll believe it when I see the MVP.
Well, other than the obvious, if not often publicly discussed, use (porn).