I agree, it will be different. The weight and importance of different acts will have different consequences. The story will need to go in the new direction whole heartedly. The question isn't one of change, but whether the change will be half hearted, or deeply integrated. If it's done well, does it matter that it's different? The only thing we lose is our expectations ...if it's done well. If it's just a fancier word for landlady, then it's a meaningless change. I can see a lot of ways to keep the story consistent in quality with the change, even if it goes in a different direction than "prodigal returns and fucks his whole family, except his dad who dies in a strange gardening accident".
I understand that the issues of taboo are changed a lot from people's epectations, but currently there's nothing in the game the is really taboo, maybe one massage that is creepy 2019 AVN trope style. It's certainly in an easier place to do this change. I guess the thing is simply waiting to see if the story content feels authentic when it's released. At least in this case we won't really know what was discarded or what parts we missed like SG.
I think this is where the crux of the matter lies, and I'm going to echo borrowed words "make things better". Anyone who has been following WIAB for a long time and/or forever knows that this was an incest story, but with twists and turns that made it more interesting than the rest. Dylan is the biggest example of what I am saying, despite his human mistakes, he is a great father and that is something you don't see anywhere.
So, what did the old guard expect? A different incest story, better than what we have perhaps.
As you say, to make it a cosmetic change is to do the same thing everyone does, to break the story now is to break the story we liked. It's the mental save that manga always keeps to facilitate the "but we're not really family" developments.
And that, it's lazy for what we've been having....
Expectations, you name that as if it wasn't a big deal, but precisely, the hype in a story is completely built on the expectations, without them, it's just another game.
Even so, we still don't know what it's about, how the change will be and what the future is, but if a change like this discards the 300 of us who have been on patreon for 17 months and earns 1000 new SS and 1000 new on Steam, well, congratulations to Ocean, WIAB will survive.