While not realistic to get the world to move to this there is a simple test - if you're still selling it and/or still protecting it with DRM then you have capability to distribute. If the answer to both is no then accessing the content where you originally bought it isn't a big issue anymore. What's a reasonable amount of access (e.g. "can I just redownload the game 24/7 for 8 years") would need to be defined but that's a much easier problem.

With the current model you run into an inherent conflict between protecting content you aren't truly relying on the monetization of anymore and what's fair to users because it requires putting the publisher/publisher's agent in front of the access.