Wonder how this will work with random websites' photo upload features. Will all other browsers break because they are serving HEVC user-uploaded content? Or will iOS transcode to JPEG on upload (triggering double lossy encoding?)
How many websites don't already re-encode most of the JPEGs they're handed? Facebook does- Flickr does, though sometimes you can request the original file specifically. Imgur probably does.
They said you can share it as jpg. I assume it works like live photos: If the receiving app (or website) doesn't explicitely say it supports HEIF it'll receive a jpg