The CSS image-set() function is now on the Microsoft Edge backlog with a priority of medium. Status updates can be tracked at https://dev.modern.ie/platform/status/cssimageset
David Stöckl commented
With srcset being supported this should definitly be supported.
Implementation should also make the width notation possible: image-set(url('...') 1024w, image-set(url('...') 2048w) which is still under consideration within the W3C draft.
Daniel Kedinger commented
This is a pretty awesomely simple way to do this. It should be supported!!