The thing about Blu-Ray is that it will probably die as a medium. Sony had the field alone but never got universal release from the producers. Now it seems more likely that downloads in a 1080 environment (or even 720 as the cable types would like to have it) will take over. Why disc? FCP to drive is equal or greater than blue-ray.
Just the opposite is happening. Sales grew exponentially in the months leading to xmas, they sold 8 million discs in December 2008 alone. The format is succeeding almost as well as DVD did in the same point in its life. The player installed base has reached critical mass. A-list titles like Dark Knight are selling 25-35% of their volume in Blu-Ray. That's huge (apologies to Paris Hilton).
Maybe Apple was waiting to see what 2008 Xmas sales would look like, and they were indeed good.
Pure file-based distribution is a nice fantasy, but not ready for prime time. Blu-Ray give you 1080p video at high bitrates (I've seen as high as 45mbps), lossless 7.1 surround, and all the extras people got used to on DVD (commentaries, alternate soundtracks, etc.). And Blu-Ray already has the support of all the major movie studios. While iTunes has less than a dozen movies in total last I checked, and only offers them in 720p, at a price of $20. Add to that the net neutrality issue and ISPs alredy throttling down so-called unlimited bandwidth on heavy users. Pure file distribution is not ready for prime time.
Plus, downloads are always going to be optimized for download speed, not quality and bitrate.
Then there are the DRM and file format issues, versus just popping in a disc anywhere you want.
We will have at least one more physical format, and that's Blu-Ray. Apple is finally realizing it.