Obviously, the game will be unavailable to play on those worlds during the maintenance, so all player subscriptions will be extended by one day due to the extended maintenance cycle. So you can’t play, but you won’t have to lose paid time. You will, of course, lose the time that otherwise would be spent earning whatever, but there aren’t exactly many weekly lockouts left at this point. And you’ll still have a month before the expansion launch.
Final Fantasy XIV, you’ve been given ample warning that the centers are moving. That’s not a surprise. Similarly, you probably knew that the move would impact your play time. The dates are in now, and you can see exactly when your play time will be impacted. The Aether data center (also known as “the one everyone is on because of Balmung and Gilgamesh”) and the Primal center will be moving from May 15th to May 17th, while Gaia, Chaos, Mana, and Elemental centers are moving from the 16th to the 17th.
Source: Official Site; thanks to Stephanie for the tip!