Not backwards compatible. We just add it to that nice cupboard "great advanced image formats we will forget about".
Society doesn't need a new image format. I'd wager to say not any new multimedia format. Big corporate entites do, and have churning them out at a steady place.
Look at poor webp - a format pushed by the largest industry players - and the abysmal everyday use it gets, and the hate it generates.
I don't really think this is the case here. All major browsers already support the new spec for example. This isn't a case of oh we'll have support for it eventually, it's already there.
> and the abysmal everyday use it gets
Estimates are that 95% of Internet users have a browser that supports WebP and that ~25% of the top million websites serve WebP images. I wouldn't call that abysmal.