|FLIF isn't supported by default in ImageMagick. It looks like there's a plugin for it, but ImageMagic is fussy enough as it is with the default configuration. Unless FLIF gets popular really quick, I don't see it happening soon.|
On that note, do any major web browsers support FLIF by default? I couldn't even find an actual .flif image to test. We aren't going to host FLIF files unless browsers will display them by default.
Additionally, the FLIF page actually states that it's still a work-in-progress and that changes may make older FLIF images fail to decode. If that happened, we'd basically have to delete all existing FLIF posts, which would be annoying since we don't have a way to search by file extension and have a policy against tags for file extensions.