They are getting another one off ebay or using a raspberry pi and controlling it with some sort of "app" (The details of which are beyond me). There really isn't a replacement with the same user friendliness.
I had a Squeezebox Duet and moved to a Sonos Connect and I much prefer the Sonos. Easier interface, less buggy, and more choices for music. Hooked on streaming Tidal through my Sonos and it sounds great feeding my Yamamoto dac.