I don't think it's a guarantee that it would get worse. less unpredictable and out there probably, but that doesn't mean it would get worse. Disney does produce a lot of very good and successful products, I have the feeling they'd manage to continue KH successfully even with someone new in charge. It just might no longer appeal to the same people as before.If Disney ever takes kh from Nomura, the series will definitely get a lot worse, but one positive of that happening is that we would get better female characters.
I do think the female character treatment would improve, but it really depends on how they'd go about it.
If they just give control over to another Shonen like writer, it's unlikely to improve seeing many modern Shonen struggle with female characters just like they did 10 years ago. While I think the writing for girls in Shonen has improved again a bit, they still don't get to be very active.
My Hero Accademia for example has a lot of very interesting and skilled female heroes in training that are always pushed aside for the male characters. Demon Slayer had some good female support characters, but they were never given much focus. A side from Promised Neverland I can't really think of any recent Shonen I read where the female characters get to take the center stage as much as the male ones do.
And I'm not sure how an American writer would deal with KH's more esoteric themes. That said Kingdom Hearts already shares a lot of similarities to Comics, so maybe someone from their Marvel or Star Wars department could actually carry the torch to a degree.