I look at as a great pastime to spend with friends outdoors (like golf, my greater passion). It has gotten me back into hiking which I haven't done in years and now realize how much I missed.
As for where its going I would think it will grow significantly for a few years as more people hear about it, but, fear it will as someone else stated, somehow get commercialized. Free listings will likely be the first thing to go.
I also hope that public areas like National Forests don't become off limits to caching, but fear that too will get spoiled someday. Guess I sound a bit like the glass is half full don't I?