Exactly, what would iTunes do with BR? It doesn't do anything with DVDs now. Unless Apple were to start including BR's "Managed Copy" scheme that would allow people to rip BR movies into some other protected format (fairplay DRM) for use on an AppleTV, iPhone, etc, iTunes really has no use for BR.
The movie studios however would love to charge $$ for this*, and linking it to Apple's payment system would allow them to easily monetize Managed Copy as an additional revenue stream, users would be able to make quick copies of their BR movies (quick depending on CPU speed of course**), and Apple can take a cut for being the platform that makes it happen. It would be difficult to monetize Managed Copy any other way - you'd have to get the user to install some software on their computer, put their CC info into some app they might not trust, and have an otherwise inconsistent experience if all five studios were to release five different apps for managed copy and downrezzing.
The MPAA would never allow this on DVDs however (its too easy to rent/rip/return), and it would only be on new BR titles because the rental channel (BB, Netflix, Redbox, etc) would get specially coded BR titles that wouldn't allow managed copy.
* Yes I know, if it weren't for the DMCA it would be legal (and free), but as long as the DMCA is still around then the movie studios can charge us to exert what used to be our Fair Use rights under the Copyright Act of 1973. **** the MPAA!
** Ripping BR movies down to iPhone res takes me 3 hours on my really fast Quad Core CPU, maybe this would get faster with OpenCL, but Apple's H.264 encoder sucks ass compared to
x264 at the same bitrate.