The MMORPG.
Director Naoki Yoshida tells the Washington Post that, if the current rate of player growth for FFXIV continues, the studio expects the game to continue for at least another five years. "Even now, our CEO is encouraging us to strive for more players and for 30 million adventurers," Yoshida says, "and he still has future plans for us. Luckily, we don't see any stopping in our momentum. At one point we thought maybe we might plateau, but fortunately our player base just continues to expand and grow."
Of course, FFXIV could continue for much longer. After all, the 2002 MMO Final Fantasy XI has continued receiving updates even now, though those updates have certainly gotten more sporadic over the years.
Endwalker is due to launch this autumn, and it'll basically turn FFXIV into Stardew Valley. (You know, besides that epic conclusion to the story so far.)
In the more immediate future, you can look forward to FFXIV patch 5.5 this April. There's plenty of goodness on the way for FFXIV fans, both now and in the years to come.