OMG we are finely getting a working toilet!

[Enkidoh]

Players really should read the whole article, as down at the very bottom SE has a disclaimer stating that they are under no obligation to actually introduce any of the winning entries into the actual game:

* If an entry is deemed to be excellent, Square Enix may decide to implement it into the game in the future. Note that there is no guarantee that winning entries will be implemented into the game.
* Entries that did not win may also be selected for implementation in the future.
* If an entry is selected to be implemented into the game, the development team may make adjustments to the design, name, or features of the item.

Because of that, plus also that they have maintained this trope in the game until now, I have to say I will be very surprised if that toilet was introduced.

hole in the ground is a working toilet.

^This. The only reference to.... personal ablutions in the game is several FATEs (Downwind in Southern Thanalan, and Unbearable in the Fringes), both of which mention most Eorzeans just use privies which are basically just a bench over a hole in the ground. Most Eorzeans are not even connected to running water let alone sewage, so a flush toilet is just too advanced for the setting, to say nothing of the trope I mentioned earlier.