Seems like their headline gambles didn't work but googling suggests that the podcast listener market increased 10% in the last year so I think they'll probably try again.
I'd say that gamble in particular worked. Not so sure others will though, audio books feels like it will be a dud.
Podcasting has also been called the slowest growing new medium in the history of new media. I can't imagine it's earning its keep, relative to those big initial payouts. Meanwhile, the shows that are brought into subscription-only world systematically fail to attract new listeners; it is hard to use podcast exclusives to grow market share. Especially the talking head variety, which exist in abundance outside the pay wall.
Will it pay off? Probably not. But is 25% a big share? Yes.
https://en.wikipedia.org/wiki/Apple_Music
https://en.wikipedia.org/wiki/Google_Play_Music
https://en.wikipedia.org/wiki/Spotify
The problem for Spotify is that they need a far bigger share of the market to be able to have negotiating power against the 3 record labels that they have to buy the music from. Apple/Alphabet/Amazon do not care as much because re-selling the music at cost or even as a loss leader is not a big deal to them.
But I agree that podcastings growth has been very slow. I think that there are a lot of factors influencing that. The biggest in my opinion is that listening to a podcast is more intimate than any other media (including broadcast radio) and that factor both slows uptake and decreases churn. Not a marketer though so just making that up.
I suspect this means that Spotify subscribers are listening to plenty of podcasts, but perhaps podcasts failed to bring new listeners into Spotify.