[planck01]

Including a futureproof decoder in every single image is a huge filesize overhead though. Or maybe I don't exactly understand your proposal.

[xvector]

IIUC he is saying that there will be a 64-bit index into a global standards-maintained table, and the decoder is downloaded from said table. Not that the decoder is actually included with the image. The decoder itself would probably eventually be cached if not shipped with browsers by default.

[amelius]

The decoder-part is the same for many images, so the idea is to store them inside a standardized codebook that is pointed to from the data.