Waning.
Not being a troll, but pinball is too expensive and requires too much maintenence, money and space to ever be super popular again.
I genuinally think it's awesome and super-romantic of people to keep the dream alive of "Pinball is coming back!!!" but people are say this ALL the time, usually after a show where all the machines were set to freeplay.
Arcades are dead. New machines are WAY beyond the average persons ownership price (and many will only see it as "What? you only get one game on it?" anyway) Older machines require consistant work at a time where everyone wants their stuff to work perfectly, all the time, otherwise they feel "robbed" or just simply can't be bothered/can't afford to put any time into maintenence.
For something that big and that expensive, only dedicated fans would commit to the time, money, patience and effort required.
As for out and about, people could possibly be tempted to play again in the wild, but again, they'd have to be dedicated, If they drain their first couple of credits fairly quickly, many would likely think "Man, I coulda bought another beer with that"
Plus they have to get over the BS alleged "embarrassment" of playing in public, which is another falling point for many.
In my opinion, the idea of this magical "one theme" game that will ignite the worlds interest falls down, similar to console developers obsession with "What ONE game will get people into videogaming?"
Some people just DON'T CARE about videogames, or football, or music, or art, they hold NO interest for them and has no appeal to their lives. You just can't convince them to "get into it" and those are fairly mainstream examples of interests. Pinball is way more niche than any of those.
The main problem with collectors opinions on this matter is that they forget that the rest of the world doesn't have disposable income and travel dedication to drop on an item that is beyond luxury.
That rules out the idea of a mass of home-owners. As for outdoor players, many places in the wild have no interest in installing a machine, and even if they do, then people have to, God forbid, leave their homes and their WEALTH of technological distractions to play, whilst simultaeniously stamping on their fragile ego fears of looking like a "geek".
I LOVE pinball with my all, but it's done. As a community we will keep it alive, of course we will, we have PASSION. But it is never going to be this thing that the public have a passion/obssesion for like they do for things more affordable and accessible, such as phones, TV or consoles.
I know this is a negative post, and I'll probably cop a ton of crap for it. But I'm only being honest to what I think. So please don't kick off at me.