"Auto-un-publish" MSI content

It would be great if we could put some sort of "expiration date" on MSI content. From the marketing side, our demand gen team is always eager to publish new content for our sales reps to use, but less often do we go in to take down older stuff. Over time the MSI folders just get too busy and over-crowded. At a certain point, less is more with MSI, so it would be great if content could un-publish itself after 3 or 6 months.