Calling all my relatives now.
Don’t panic. It’s FUD… a false report about an old, little used cloud service that is being discontinued that has nothing to do with photos on iPhones. Unless you or your relatives opted into sharing your selected photos from the cloud with non-Apple users, then you’ve got nothing to worry about, and even then it would be ONLY if you had a unique photo that ONLY existed in that shared photo on My Photo Stream that you would lose. That’s a very unlikely possibility.