yeah, most of this DnD stuff won't be worth much at all, other than the small press, short run books that also happened to be exceptionally good. For example, in ten years, a pristine, unused copy World's Largest Dungeon would be a great collector's item.
As for the minis, i hate the way WotC does this, but it's genius marketing wise. Introduce a good product, pull it off the shelves quickly, and drive up demand. Fortunately, i've been collecting minis for years and i have most of the "groundwork" fantasy archetypes. The minis i like best are the quality monsters, which have always been harder to find even in pewter or lead.