I don't really care much about any of this.
Ok, it's mildly disappointing that they are releasing yet another ebook format, but it still doesn't matter that much from an end-user perspective. At some point, the format will be editable and I'll just carry on using Calibre to manage my book collection, same as I've always done. Epub would have been preferable and easier all round, but it's not big drama.
As long as I can get the books I want on whatever Kindle I happen to own at the moment, it's all good!