I will now (in a few words) try to explain to you why it is NOT profitable and why it will never happen.
Creating XXX games is essentially not very legal and there are a lot of pitfalls (in some countries direct distribution is generally prohibited, for example GERMANY and KOREA).
If you legalize this business (in Germany- it may still be possible, but in Korea- you will not be allowed to do this), then the developers will have to give a very large % to the state as a tax, and since they (most developers) do not work officially and as outsourced (from different countries), then it is difficult to attract them. And no one will spend energy on work that will ultimately bring you (even legally) very little profit. And so now the whole policy is on voluntary donations and a minimum payment of % tax to the platform itself.
No matter how the government puts a spoke in the wheel, there will always be ways around it (for example, finding a third person who will take on the role of the main one, but in fact has nothing to do with the project and is located God knows where, and the main team of developers are shadow workers).... And I don't think that from the recognition of the ADULT industry, games (suddenly) will become better. On the contrary, this can leave many indie developers without work.
And there will always be offended people who, for one reason or another, will come and block your product, simply because THEY didn't like it for some reason (even STEAM had such examples), although, if you think about it, it's still absurd. And in the end, you will be left with no profit at all, and you need (you are obliged) to pay WORKERS a salary if you decide to switch to official working conditions. And that's why now everyone works on pure enthusiasm and in their free time, and for most XXX game developers, this is more of a hobby than their main income. (Well, and in rare cases, these are scammers who milk their Patreons for months and feed them useless updates, if they did it according to the LAW, they would not act like this and a class action lawsuit could be filed against them, that they are doing stupid things, getting money, but doing nothing, but they are happy with everything -_-).
So there are two sides to this situation.
So draw your own conclusions.