JXL is an interesting standard. Integrates a recompressor that shaves ~20% off .jpgs without further loss(!), FUIF for essentially-lossless images in a progressive/interlaced mode like this, a separate lossless format, and a new lossy format with variable-sized DCTs and a bunch of other new tools (other transforms for DCT-unfriendly content, postfilter for DCT artifacts, new colorspace, chroma-from-luma...). It's intended to be royalty-free.
I'm not sure if putting it all under one standard will make it hard to adopt, and/or if AVIF (based on AV1) will just become the new open advanced image format first. Interesting to see in any case.
I think the progressive loading feature of FLIF/FUIF/JXL would be really interesting for WebGL. WebGL games already have asynchronous resource loading and incremental image decoding/texture upload just by virtue of using the available APIs. One could get a pseudo texture streaming effect by default (although no unloading of textures...)