We’ve making progress on the responsive image front in modern browsers, but alas, we’re at an impasse. As noted by Opera rep Bruce Lawson:
The outcome of the meeting was that
…The Paris meetup’s most immediate outcome was agreement that srcset + DPR-switching is the right initial step forward (i.e., the 2x, 3x, etc. syntax).
Bottom line, the consensus is moving toward srcset over a new picture element but no modern browsers are yet shipping with it.