My thoughts on this (I'm typing this upat close to 4 in the morning and it's cold, so pardon me if my thoughts seem short and scattered at times):
Pinball is growing, but it's not yet big.
That being said, "big" is a very subjective term, and what may be big to one person may not necessarily be big to another. To me, pinball has become big when it is a common enough sight and knowledge on it is widespread enough for it to be mainstream. It is not there yet, and far from it. I am also talking about pinball as a whole, and level of familiarity with the general public, not specific things like competition or specific sectors like the bar scene in Seattle.
There are more people getting into it, but for whatever reason, word of mouth doesn't really spread very easily in pinball compared to some other things. Someone might be introduced to pinball, but I hardly ever see those somebodies introduce other people to pinball after that. There's no chain recommendation here that's necessary for word-of-mouth buzz the way it happened with, say, Paranormal Activity or Splatoon.
I know the first post was comparing pinball competitions to eSports, and whole eSports brings in millions of viewers, it's still just a tiny part of the video gaming landscape. For every person who plays Ultimate Marvel vs. Capcom 3 and competes at EVO, there are at least ten thousand others who don't. For every person who gets an invitation to the Pokémon World Championships, there are at least a hundred thousand others playing those same Pokémon games who don't.
Something else to consider is mobile gaming. Mobile gaming is currently the dominant kind of game people play to pass the time, which is what pinball used to do. Pinball was successful in earlier decades because of a lack of competition. For pinball to become big again, it has to wrest that away from mobile gaming, which I don't think will be happening any time soon considering the sheer presence games like Clash Royale and Bloons are having on the general public. For better or worse, they are giving what the mainstream wants, which is cheap, quick, accessible games. For that matter, mobile games are currently eating away at traditional console video games (which, in turn, destroyed the arcade video game scene outside of Japan).
This is, of course, talking only about the Anglosphere. (And from what I can gather, pinball's popularity seems to be at roughly the same level between the United States, Canada, Australia, New Zealand, and the United Kingdom. I don't think it's really up there in South Africa, Liberia, Belize, India, and so forth though.) I can at least say that in the west, if pinball isn't big, at least you can expect people on the street to know what pinball is, even if they're outdated depictions as seen in mass media. At least they recognize the word, and they know you play it by hitting a ball with a flipper by pushing a button. During my trips to Asia, I cannot even say that much. Again, with the exception of Japan, there has never been much effort to import pinball machines over (and who can blame them, considering shipping costs?), and as a result, even that level of familiarity is lost there. In one of my previous jobs, I worked with people doing community service. One of them had immigrated over from China a few years ago (I think he's here for college) and asked me what I was into. When what I listed got to pinball, he asked me, "What's pinball?" and I had to explain to him what it was. I don't think he really understood even after that.
But yeah, pinball has a lot of hurdles to overcome. Some of them that I can think of include (in no order):
1. Grabbing attention away from people into mobile gaming.
2. Standardize a card-based system of payment, because a lot of people don't carry cash anymore.
3. Having it in places with high foot traffic. Place them in bars all you want, but you won't get a lot of visitor traffic. (At least, the bars around here don't. Almost all of them are strictly for locals.)
4. Overcome the maintenance hurdle, which is why operators would rather have those Neo•Geo collections I see everywhere.
5. Grabbing attention away from people who would rather play prize machines, like Key Master.
6. Dealing with whatever it is that causes word-of-mouth to rarely spread beyond first-degree.
7. Maybe traditional advertisement in some way.
8. And the biggest thing of all is accessibility. It may seem really obvious to you and me, who have been into pinball long enough to understand its nonverbal language, but to a beginner, it's not! Something as basic as starting a game, or how many balls you get over a game, or a phrase like, "Lock is it" is not obvious at all to a beginner! Just two weeks ago, I had to demonstrate the start button to someone, as he was 100% convinced the machine was busted because he inserted in some quarters and the game didn't just load a ball onto the plunger. He left after the first ball; looks like he thought the game ended there. (I made a topic here specifically addressing things obtuse to beginners.)
That being said, I do find it interesting there seems to be an earnest effort to try to make pinball more popular. In a lot of other fandoms I'm a part of, there's a strong contingent working to try to keep it niche. (You know, "It's Popular, Now It Sucks.")
One more thing: When I see pinball in places like Round 1, they are located by the bar, away from all of the other arcade machines. I see that as a problem. All the people come in and they go play the other machines, and most don't even know the pinball is there. Even if they're not interested in pinball, they don't notice them. I don't know if that's a problem with the people who run these arcades not considering pinball as the same as other arcade games, or if it's a problem with the pinball business not aiming them at the BlazBlue crowd these arcades gather though.
I may have more thoughts later, but these are what come to mind right now.