Lego frequently moves collections out of production and into what brick enthusiasts call "retiring sets." These retiring sets don't have a particular timeline for when they will become unavailable from retailers but they are being moved out of production so they become harder to find. Below you'll find a table, updated for 2017, that shows the latest lego sets being put out to pasture by the company. I have some reviews on some of the collections and we will continue adding them as I can get my hands on them. Some are already hard to find.
If you have even the slightest interest in any of the sets presented I recommend buying it while you can as there is no telling when one of the prized lego sets will be discontinued.