On my cruise on the Fantasy in January, I noticed that Quacks was gone! AbDUCKted! It must have been removed in the Fantasy's dry dock in the middle of 2017. Now that I think about it, Quacks wasn't on the Dream either.
On the Dream-Class ships, Quacks was pointless. Whozits and Whatzits is a shop on deck 11 (the pool deck) in the Midship elevator lobby. This store sells everything Quacks had, plus clothes, books, and various other items. It's as convenient as Quacks was, and there was no need for both.
Since the Wonder and Magic don't have Whozits and Whatzits or an equivalent, there is more of a reason to have Quacks. But what's the point of having something that never gets used? Since it was removed from the Dream and Fantasy, it nearly confirms that Quacks will be removed in their next dry docks. The Magic is scheduled to have a dry dock later this year, so we'll see what happens!