I have a friend who lost her only child in a car accident several years ago and it just about devastated them. It was so sad. So I understand about the 'different' kind of empty nest.
I will say that they went on to have a couple more kids after a few years. They were young when they married but had decided to just have one child. They do still miss their first son a lot and talk about him often.
I imagine it is very hard for some parents to lose a child other then them leaving home for college, etc. I certainly feel for them after what I saw my friend go through.
Thanks for starting this, I hope it will help some get through their heartbreak.