I was able to tell you a few weeks ago that Philips Hue is planning to kill off the Sync app as well, following the end of the Bluetooth app. Instead of a separate app for the Philips Hue Play HDMI Sync Box, the entire functionality is to be integrated into the normal Hue app.
This is not really surprising, because the Hue app already has a section for synchronisation, for example with Spotify. And the entertainment areas that are created for syncing with the PC or the Sync Box are also configured in the Hue app.
At the moment, you are still redirected to the Sync app from the Hue app, but this diversions should soon no longer be necessary. After all, Philips Hue already shows in a support video how to start the sync via the HDMI Sync Box in the Hue app: