See, I'm not so sure about that. Finishing the story is what people want from this game, as evidenced by the constant clamor for that in this thread. Would people continue to support the game after it was finished and they got what they wanted? Some might, but I figure many wouldn't. And sure, you can point to Hornstown and maybe a few other games that pulled it off, but I can point to literally every other videogame regardless of theme, genre, or budget, since most game devs avoid this kind of thing like the plague. Even ongoing service-based games like MMOs either keep perpetually extending their overarching story with no definitive conclusion in sight or simply advance the story at a glacial pace (I'm looking at you, Warframe).
Worth noting, it doesn't actually matter who's objectively right and whether finishing the story would cause a drop in financial support or not. What matters is whether Inno believes that it would.