I can't speak for myself (I don't listen to that many podcasts), but my friends who do seem to do so mostly through Apple's Podcast app, Spotify, or a similar service.
RSS might be providing the syndication under the hood to these services, but it's firmly an implementation detail at this point and not a thriving protocol/community in its own right. Which isn't to say that I want it to fail or be replaced with something else, either!
Yeah, I provide an Atom feed for my blog. It has about ~100 subscribers across a few different RSS subscription services, and I get a few hundred independent RSS client requests a week. Don't get me wrong: it all works really well, and I like providing it! But it's a very small fraction of my overall traffic, and other bloggers I've spoken to have indicated the same.
How do you tell, technically speaking, that someone is subscribed to your feed? Is it logging requests of the RSS feed url somehow?
Doesnt Feedly, for one, aggregate RSS subscriptions for all of its users? If I were subscribed to your blog through Feedly, would you see me as an individual subscriber, or all of your Feedly subscribers as one subscriber? If so, I imagine this would deflate your numbers.
I'm not sure it is a community in the sense that you or your friends would recognize, but it is there. I use AntennaPod, and it relies quite a lot on RSS and Atom feeds, as do other podcast apps.. Submitting your podcast to major services like Apple iTunes using RSS is not a mere implementation detail, but a de facto standard.
RSS might be providing the syndication under the hood to these services, but it's firmly an implementation detail at this point and not a thriving protocol/community in its own right. Which isn't to say that I want it to fail or be replaced with something else, either!