It's maybe not a "good" thought, but it brings to mind the idea of using this technique for a proprietary format (webp with a header change, say) to make images only work on your own website.
Typical users wouldn't be able to view downloaded images; they could only see them through your site.
I'm not sure on the details of web assembly, but if you can obturate the workings then this technique becomes stronger, can web assembly be delivered compiled?
