If the network files systems appear to native applications like ordinary files saved on the local hard drive, then it should be possible even now, I think. I'm not familiar with these network shares, so I'm not sure how to test them. Does the network file systems get mounted onto the user's computer?
I agree about https/http. Needing to set up a Web server when you already have a secure file system seems like a lot of extra work that would also be difficult and inefficient to maintain, because you would probably end up with a lot of files getting duplicated.
Is it possible to set up a test network that uses smb/cifs, maybe using AWS infrastructure? If yes, I was thinking we could try it out.