Mozilla is more than willing to adopt it. They just won't adopt the C++ implementation. They've already put into writing that they're considering adopting it when the rust implementation is production ready.
- https://github.com/libjxl/jxl-rs
- https://github.com/tirr-c/jxl-oxide
- https://github.com/etemesi254/zune-image
Etc. You can wait for 20 or so years "just to be sure" or start doing something. Mozilla sticks to the option A here by not doing anything
zune also uses jxl-oxide for decode. zune has an encoder and they are doing great work but their encoder is not threading safe so it's not viable for Mozilla's need.
And there's work already being done for properly integrating jxl implementations with firefox but frankly things take time.
If you are seriously passionate about seeing JPEG-XL in firefox there's a really easy solution. Contribute. More engineering hours put towards a FOSS project tends to see it come to fruition faster.
> To address this concern, the team at Google has agreed to apply their subject matter expertise to build a safe, performant, compact, and compatible JPEG-XL decoder in Rust, and integrate this decoder into Firefox. If they successfully contribute an implementation that satisfies these properties and meets our normal production requirements, we would ship it.
That is a perfectly clear position.
Seems to be under very active development.
That's a perfectly reasonable stance.