Yes, but they're not going to pass on costs from not using a voice actor. They're just going to charge what they normally would have, and not worry about having to give so and so a cut.

Sure, and then we'll get more audiobook options, as it becomes economically viable to make more niche stuff into audiobooks.

Niche stuff has always been economically viable. Niche stuff also tends to get publisher support. Realistically these days the only reason why books don't have an audiobook format is due to not wanting to support Amazon/Apple, or because they just don't want it. Voice actors literally are not expensive for audiobooks. You can absolutely afford one if your tiny $9 book hits more than 200 copies.

Unless you're talking about illegal niche, in which fair but I highly doubt stores are going to accept those. All generation helps with is content that will be free.

I think you’re underestimating how much work goes into hiring and producing something. Making it more self-service will go a long way toward making it more accessible to small creators. And my impression is that many books don’t sell 200 copies.