Much of that lack of updated promo, previews is probably because the change in the premiere date was so last minute. I think they just dropped the ball. After all, Game of Thrones had an anachronism of a Starbucks coffee cup in this past Sunday’s episode.
With the finalization of the last half of the season only now in focus, and with upfront this coming week, I think the promo monkeys had their hands full. And if they need fill to do updated voiceovers, there may simply had not been time.