The <picture> approach also has a sort of solution for degrading gracefully in older browsers. You can nest an <img> in your <picture>. Newer browsers are supposed to ignore it, older browsers would ignore the surrounding <picture> element instead.

I think there are other good reasons to prefer the srcset approach, but not this one. The email here provides motivation: <http://lists.w3.org/Archives/Public/public-whatwg-archive/20...;