I suggest to add a procedures like "Despawn Gem " and global trigger "On Gem Despawn". For items of course.
Thank to these procedures it'll be possible for example make a self-plant trees. Just throwing sapling on ground and when this item is about to despawn, then sapling block will be placed.
Other example it spawn baby chicken on place where egg(item) does despawn.
I think that there would be other ideas about this way.