Looks like this Rollercoaster may have come to an end.
https://s.famitsu.com/news/201709/24142632.html
From what I've gathered from Google Translate, it seems that Tabata and crew were just doing testing on whether the Luminous Engine or the Unreal Engine 4 would be a better fit to use for the Switch, but that somehow got translated as FFXV coming to Nintendo Switch.
In this article he says that there are currently no plans for FFXV on Switch.
He did say that UE4 performed well so there may be hope for other games from Square.