I wouldn't say that it's a landmine.
As consumers and business owners, it's great wonder. Most of these VN projects often struggle with timing and schedule because of how much time it takes to do the art and render everything. Creators will have excellent stories that they finish the writing in a week or less but take 2 months to render like 5 scenes. Almost all of the best games on this site have taken 2 or more years to complete, or are still in development after many, many years.
But for a great counter-example, look at the gay game
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on itchio. The creator has a great story and hot scenes, and finished the whole game within a year, just because he used AI to generate images. And its FREE. I don't know any but there's probably alot of straight games using AI out now too.
However, morally, I do agree that it puts alot of artists out of business, especially those on patreon or other websites that make most of their money with special commissions. But hey, that's just the hand of the market.
Right now, this game has EXCELLENT writing and super hot scenes, but they could definitely be supplemented with hot AI-generated images.