Generally a smart hedge for Nintendo (any platform holder should offer as much of the toolkit chain as possible so they're not dependent on anyone else, while still offering great support to third parties who want to offer their own version of any part of that chain), but I think their best bet would be cultivating a strong relationship with Epic to make sure the Switch is a first-class citizen as far as UE4 optimization is concerned ('optimization' being the key word there - obviously more powerful hardware will be able to do things the Switch can't, but Nintendo should make sure that crossplatform ports to Switch are as easy as possible).