Yet, I think it's really hard to change what has stuck. The gains have to be enormous to warrant the hassle of trying to keep publishing in and supporting a new image format until it just works for everyone.
The reason we have PNG and JPEG is that they are, all in all, more than good enough. Yes, the dreaded "good enough" argument surfaces again stronger than ever. They are also easy to understand, i.e. use JPEG for lossy photos and PNG for pixel-exact graphics. But most importantly they both compress substantially in comparison to uncompressed images (like TIFF) and both have long ago reached the level of compression where improving compression is mostly about diminishing gains.
As there's less and less data left to compress further the compression ratio would need to go higher and higher for the new algorithm to make even a dent in JPEG or PNG in any practical sense.
Also, image compression algorithms try to solve a problem that has been gradually made less and less important each year with faster network connections. Improvements in image compression efficiency are way outrun by improvements in the network bandwidth in the last 20 years. The available memory and disk space have grown enormously as well.
For example, it's not so much of a problem if a background image of a website compresses down to 500Kb rather than 400Kb because the web page itself is 10M and always takes 10 seconds to load regardless of which decade it is. If you could squeeze a half-a-megabyte off the website's image data the site wouldn't effectively be any faster because of that (but maybe marginally so to allow the publisher to add another half-a-megabyte of ads or other useless crap instead.