Everyone seems to be focusing on the console's power, while forgetting something:

FFXIV requires an internet connection to play.

Unless I'm thoroughly mistaken, the Switch doesn't have an LTE chip (you'd need a SIM card and a mobile data subscription to use it).

In order to be mobile with FFXIV on the Switch, you'd need to tether through your smartphone or hijack someone else's wifi.

Technical aspects of the console aside, I think that presents a pretty glaring problem with porting the game to the Switch.