It wouldn't surprise me if you end up with something of a bifurcation. Relatively simple podcasts by people doing it for fun or supporting them professionally on the one hand and professionally-produced podcasts that make money on the other. Of course, that's an oversimplification and at least some number of people will devote lots of time to podcasts even though they're just making a few dollars from fans through Patreon or whatever.

Right, the business model is getting nuanced with revenue from YouTube / Patreon etc... Some will continue to do it as a form of marketing. Also, there's a non-monetary social status benefit that will cause people to continue even if it's not a money maker (that you are alluding to). Like most other human activities it will follow something of a uneven distribution where 20% of the podcasts get 80% of the views (or something like that).

Teasing apart motivations is hard.

There's definitely the "egoboo"factor, a term from the early days of user-generated content that has sadly passed out of use

For many, they're definitely a way to increase professional recognition, promote a consulting business, improve customer engagement/awareness, etc. i.e. brand building/content marketing

For some, it's a hope that they are going to hit it big though this probably applies more to YouTube and Instagram. (And, if there is a bubble, this is probably the main reason.)

The fact that even just a few thousand dollars is worth putting a fair bit of effort into for many.

Or a complicated mix of all of the above.