You'd have a situation anyway where it would be like this
Call of Duty PS4 - 6 million copies
Call of Duty X1 - 4 million copies
Call of Duty Nintendo - 100,000 copies
Even if programming between the machines was easy I couldn't really fault some third party devs for not even bothering. Company resources are finite.
People who like third party games all own a Playstation or XBox already, they're not going to buy a new console to play the same games and then also have the situtaion that their friends don't have the same console, so they can't play them online either.
Nintendo will bank on NX being a hybrid type platform that basically makes the portable the star of the show I think. If that doesn't take off (the console part of it anyway), then I think they'll go console third party and just continue to make their own handhelds for a little while longer.
