My understanding WRT buying a movie on iTunes was:
1. If you download the movie, you will always have the ability to play the movie you downloaded.
2. As long as Apple has the rights to distribute the movie, you will be able to re-download it again
3. If Apple loses the rights, and you don't have your own backed up copy, it's lost.
It's the same for Audible books; which is why I always d/l and backup any movie or book I buy electronically.
Buying a physical DVD is only #1. If you buy a physical DVD at Walmart or whatever, and then lose it, you can't go back to Walmart and ask for a second DVD; that's a perk of buying an electronic copy.
Compare this to buying a piece of software off a website for $30. You download the installer, install it, and use it. Six months later, the company goes out of business and the website does down. You can still use the software as long as you still have the installed version and/or the installer; but if you lose the installer, you lose access.
I guess the difference is that Apple is purposely blurring the line between "storing stuff in the cloud" and "redownloading" movies. What should really happen is that three months before Apple loses the distribution rights, they should send an email to everyone who's bought the move, telling them to either 1) Download it to their own local hard drive 2) Buy an iCloud subscription and click this button, and Apple will automatically "download" it from iTunes to your iCloud folder on your behalf. (EDIT: Which due to [1], will probably require actually shipping bits over some internal network for each individual user.)
[1] https://en.wikipedia.org/wiki/UMG_Recordings,_Inc._v._MP3.co....