Well considering I plan on doing a lot of traveling, maybe living abroad too, someday I don't expect to keep many things that revolve around pokemon. No doubt the games, game cases, pokewalker, some pokemon cards, figurines, and plushies (if I get more) will be collected but only enough to where I can move them around with me from city to city, apartment or house to house easily.
What I wonder really is where pokemon will be by the time I have kids and they're old enough to understand what pokemon is. I expect that to be sometime in the 2020s, which is an awfully long time in the video game world. So..who knows maybe they'll already be into the pokemon around then and I'll just have to introduce the older ones.