I have been searching (unsuccessfully) for a reliable method to lazy load images while using the HTML5 spec for . Most solutions/plugins out ther
For anyone still interested... After revisiting this issue, I came across a fairly new script called, Lazysizes. It's actually quite versatile, but more importantly it allows me to do lazy loading of images while utilizing the HTML5 markup as described in the OP.
Much thanks to the creator of this script, @aFarkas.