I was at a Marantz/Denon launch of their latest range a couple of weeks ago and they said they will be making their platform completely open and available to third party control, so no reason why not...
Interesting someone else trying to knock Sonos off the perch though... I queried whether HEOS would be on board on their receivers which would have made sense, apparently not this series but the next it will be on board which would make their 5 & 7 speakers more viable imo. The app wasn't too bad though, certainly better than the Sonos' latest effort! terrible app!