Has there been an "everybody is listening" style hit since Serial? No. And I strongly disagree that it is even a desirable outcome. It is just something that happens extremely rarely in democratized content where the barrier of entry almost doesn't exist. This creates a landscape where an infinite number of niches can form and provide more content than you could ever listen to. Do you just want to hear discussions about philosophy? video game sub-genres? an author's books? sports team? Fantastic, there is probably hundreds of hours of content for you to listen to (or reject due to quality reasons). This does create an environment where "famous talking heads" can flourish, as mentioned in the article, but as long as the barrier to entry is low and the podcast platforms remain open, it also creates an environment where a terrific variety of content can flourish.
What Serial did was get millions of people to investigate that Podcast app on their phone, but instead of then just bouncing to The Next Great Over-Produced Narrative Podcast they discovered there was a massive, and growing, number of podcasts that spoke directly to them. I've been podcasting since 2014 and the really interesting thing that happened after Serial got big is that I didn't have to describe what a podcast was anymore. That is why Serial was such a big deal to podcasting.
All the Podcast companies trying to replicate the success of Serial are, in my mind, chasing a mirage. You can recreate the quality of the show, but you can't recreate the environment that it was released in, and it was that environment that made Serial a "hit".