Realistic part II - you'll never get all engine coders and mod developers to agree on a single replacement format for sprites (or any other type of file for that matter). Everyone will always have their own ideas and will end up pulling in different directions. The ultra trads will bemoan the new format(s) and contend that .spr was perfectly fine, thank you very much. DarkPlaces (I think) has a format, but it hasn't exactly been widely taken up, at least outside of DP-specific work.
There have been efforts in this direction in the past with other things (anybody remember BSP 30? Heffo's texture format?) and - with the exception of LIT (probably because it was documented and some clever clogs *cough* wrote a tool to automatically light ID1 maps in colour) - they've all gone into limbo. Look at the protocol discussions as a classic example.
Hell, we can't even agree on which directory skyboxes should go in.
Anyway, I do seem to go on about this a bit, don't I?
