Quoted from ZNET:

I agree with the general observation that an aging marketplace of likely buyers fuels a downward price trend. It's axiomatic that prices are proportional to demand. The model train market is another such example.
Nevertheless, my view is that the pinball hobby is more complex than the vintage pocket watch hobby, for example. This is because pinball enthusiasts do not merely collect machines. Many enthusiasts enjoy the restoration aspect, both technological and artistic. The social feature of pinball, both in home collections and in tournament locales cannot be overlooked. The multidimensional attraction offered by pinball (and arcade games, for that matter) is what compels me to conclude that pinball is here to stay, with ordinary popularity peaks and valleys.
Pinball enjoys an Americana sensibility which has denizens of fans worldwide. Arguably, pinball as a hobby occupies a unique cultural niche which is firmly entrenched in the American psyche. Well, that's my opinion. . .others will surely disagree.
Pocket watches, which are as much an item of fashion as a timepiece, tend to sit in drawers or in display boxes. Their utility was long ago supplanted by wrist watches and cellphones. Moreover, they have lost their fashion cache. Consequently, younger generations have no pocket watch life experience rooted in their memories. In contrast, kids of a new generation are growing up in households with substantial pinball collections. While many such kids will eschew pinball for their Xbox games, many others will wish to revisit their childhood memories when they too have disposable income.
Apart from the generational influences upon all hobbies, the primary point of my post is that intrinsic aspects of pinball coupled with multiple "attract modes" to the hobby itself transcend that singular factor.