if you want to be pedantic, they can't delete it off our device. They just delete it off their server and then when you phone home to verify your movie they can say "sorry we can't play this".

Or at least, that's the streaming way. If this was a digital download with on need to phone home it will in fact be stuck on your PS3/4 unless they force you to update to do anything with your PS3/4. From there they can probably delete it during a patch. but the PS3 is well past EoL for that.

Many DRM systems do not work offline or at least require a login/reconnect every few days and even if it would work offline the kind of users that would buy a movie on a playstation are also the kind of users that would connect it to the internet.