I pretty much agree with what Darin says and don't see the popularity of this hobby decreasing any time soon. But my philosophy is that I'm in it for the long haul anyways. If things peak sooner, then some of my collection may lose value. But it also means I may be able to buy things that I figure I'll never get a chance to own.
My parents started collecting antiques (stoneware, primitives, etc.) back in the early 70s. Some of their stuff has maintained value while other items have lost value, or at least have not kept up with inflation. But they don't really care because they've been able to surround themselves with the stuff that they enjoy for nearly 50 years.
Joe