We had an extension for the living room and planned where the tv would be mounted on the wall for ultimate viewing angle wherever people sat in the room yes its a TV viewing room what else do people do more of in the living room. When we got our 55" it was really big at the time for a TV but tvs have grown since then. Fitted with a surround sound system we stopped spending money going to the cinema too.9 to 12 feet, depending upon where seated, and a 49" set, as above, make sure it's at eye level when seated - we find that adequate for our viewing. Larger would dominate, and turn it into a TV viewing room.
So yes the next one will be bigger.