I'd like to bring up the concept that data doesn't really go away. Companies can claim they've deleted it or say whatever the heck they want, but it has been rolled into other things by then. There are derivatives of it and they probably did keep some backups.
I would focus more on the data becoming stale after a while. Therefore, implement new rules, regulations, laws, to tighten their ability to collect the superfluous amounts of data, and let that other data become stale, old and of no use because it's so old. Don't worry about trying to wrest it out of their hands, because you're never going to.