The funny thing for me is that this would force me out of the Amazon ecosystem. I've purchased hundreds of Kindle books, but I read them as EPUBs on my Boox. If I can't back up my purchases as EPUBs then I'm not going to buy from that vendor.

I hope Amazon knows what they're doing, I suspect that as always fears of piracy grossly outweigh the actual financial impact of piracy. Moreover attempts to battle piracy rarely seem to inhibit the pirates.