That sounds like a very interesting scenario, but I don't really know what would've happened if she didn't regress. It certainly could've been much better than having Casca be a "Vegetable" for 200 chapters and be useless.
But even if the studio or a fan can capture the atmosphere and tension that Miura provided us, wouldn't be fair to give them chance, even if we know that it won't be the same type of writing quality as the Manga?