This particular page is only talking about a change to Microsoft's ebook store. On Amazon's side, they've been updating their docs to talk about how MOBI is "d

This particular page is only talking about a change to Microsoft's ebook store. On Amazon's side, they've been updating their docs to talk about how MOBI is "deprecated", but the only actual change announced is that MOBI support has been removed from the "Send to Kindle" (via email) feature. So if you're not using that, you should be unaffected.