I doubt they would do that. Nintendo's internal teams have very competent engInes like the Monolith Soft engine which would be better suited to RPGs.I'm still excited to see what Nintendo's first-party UE4 game is. I like the idea of it being Fire Emblem.
Its obviously Metroid
Retro studios are competent enough to make their own game engines. Unreal makes sense for smaller developers. But bigger developers like EA (Frostbite) and Ubisoft use their own engines.