I see pinball collecting as a multi-level platform that ladders both up and down.
Like anything else, people with more income buy the higher-end pins and those without the means buy lower-end pins. Those that can fix them up, like to repair, or can only afford "better" pins by repairing them do so...and often sell to higher end buyers. Space concerns cause trade ups or trade downs.
The prospect of a new pin or sought after machine cause people to sell, trade, and save up to get into them.
No...i don't think that pinball has peaked. I think websites, barcades, podcasts, forums, and the like have brought it more to the forefront. We see more sales and buys than ever before. That is the sign of a solid collectorship...not one that is deteriorating.