As for the possibility of an actual Apple branded HDTV with an Apple TV style interface built into it, that seems more of a long shot. With HDTV sales down and what really amounts to a lack of interest by consumers, it would seem that the space for Apple to offer a high-end HDTV offering just does not make sense at this point in time.
With Amazon showing off the new Fire TV, it would seem that voice control of some sort is for sure a given for the new Apple TV and some sort of at least casual gaming support is a given. As for other abilities, that is more of the unknown, but for sure expect the new Apple TV to sport newer and more advanced and upgraded hardware to make it better prepared for the future.
When Apple will release it is the biggest question. Sources suggest that they might want to not wait very long as the need to be competitive and not surrender the in-roads it has made with the Apple TV in the living rooms and family rooms.