A recurring problem is that a linked resource may no longer available after a course has been published.
Recent examples of this are when a newer edition is replacing an older edition, or when a resource was pulled due to plagiarism.
Downsides to updating a course involve time and money, as well as forcing the user to buy a newer edition for an older work they may already own.
The downside to not updating the course means that portion of the course can't be viewed. Depending on how often a resource is linked, that might account for a significant portion of the content.
Something needs to be done to avoid the unpleasant situation of buying a course which you discover can't be completed:
- The easiest solution to work around this problem would be to automatically unlock the older content for people who own both the course and the newer resource. This wouldn't require any update to the course (although the user wouldn't be reading from the most recent edition).
- A more complex solution would be to add some sort of dynamic linking, to show the original content when the user owns an earlier edition, and the newer content when the user owns a later edition.