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.