There have been multiple proposals to replace JPEG, including PNG and two that have been officially adopted as alternative standards by the standards group JPEG, but yet are widely ignored: JPEG 2000 and
JPEG XR proposed recently by Microsoft. None has made a dent in the dominant position of JPEG as a final display format, and indeed as the in-camera recording format for the vast majority of photography, and I doubt that BPG has the slightest chance. The best hope for progress is a backward compatible upgrade, like the most recent update of the existing JPEG standard to
JPEG 9.1, which adds options for 12-bit encoding and lossless compression.
My reasons?:
1) The DR argument is mostly irrelevant even before that 12-bit upgrade of JPEG: as already mentioned, the 14-bit of some cameras and the 10 bits of coming displays is a linear scale, whereas JPEG is 8-bits on a gamma-corrected scale that assigns proportionately more levels in the shadows, so that it can hold more dynamic range than a 10-bit linear display, or even a 12-bit one.
2) Saving space is the other big argument for alternatives to traditional JPEG (better IQ at a given compressed file size or smaller files for a give IQ) but storage is becoming cheaper, smaller, and more abundant far faster than the resolution/DR needs of image files are growing, so the size argument is becoming less and less relevant.
3) JPEG is massively entrenched, so a backward compatible upgrade is the only approach with much hope of success. (Even JPEG 2000 and JPEG XR are not backward compatible.)