I think it is quite tricky to argue that StudioCanal did anything wrong.

Sony isn't a naive child, they've got whole armies of lawyers analyzing the deals they sign. If Sony knowingly signs a horrible deal (such as a Netflix-like "you can show this bunch of content to users and let them download it for X years") which due to their desire to sell movies leads to them inevitably getting screwed over on their (now-mandatory) contract renewal, that's on them.

Either Sony should've insisted on a contract which included a right to sell perpetual sublicenses, or they shouldn't have "sold" those inherently-temporary movies to end users. It really is that simple.