Ever since I heard about JPEG 2000, I have been waiting to see a new, efficient image format replace JPEG (1992). Needless to say my wait is getting long.
But now a new format is promising even more than JPEG 2000. JPEG XL could replace not only JPEG 1992, but PNG, uniting both lossy and lossless compression into a single format. And according to an excellent presentation by Jon Sneyers, there's good reason to believe this time will manage to take photographic compression more than 2 decades forward! According to the latest press release, reference software should come in Q4 2019.
Crossing fingers Santa will be most generous this year...
2022-03-02 update
Santa has struggled in the last years 😑--
And software patents may further prevent his work.
2022-11-19 update
JPEG XL has made great progress in the last 14 months. A first version of the file format was published in October 2021, and reference software was finally released in August 2022! JPEG XL provides an up-to-date slideshow about itself, which explains that the standardization process continues. Google's removal of (experimental) decoding support from Blink (affecting Chromium) has however created some confusion.
2025 update
Microsoft adds JPEG XL support to Windows 11 with a quick download