The Rumors are Just that - Rumors
Trust me - ADT is still being developed and in fact, the ADT development team is probably larger now than it ever was in the past. Autodesk is putting a lot of resources into both ADT and Revit Building. Neither product is going away now, or for the foreseeable future.
So if you're using ADT and are using it effectively, don't let idle gossip and false rumors keep you up at night.