The Stern Bubble will burst when "Peak Pinball" is reached.
It's a simple equation: There is a limit to how many machines current enthusiasts can physically find space for. Once all their 'man caves' are full, the bubble will burst, unless more new enthusiasts keep entering the NIB market.
Personally, I hope that is a long time away, and that more new enthusiasts will convince their wives they have space for their first machine in their homes.
I think I persuaded a friend this week to buy his first machine sometime this year. How's everyone else going in the quest to persuade more people into owning a pin?