I guess in more modern times, the closest parallel I can think of is Hyrule Warriors Legends, where the game was clearly meant to be played on a N3DS, but can still be played on an standard 3DS, albeit with horrendous framerate.
Good comparison, although HW Legends isn't sold in a "*NEW* 3DS" box like Xenoblade 3D was. It's not marketed as a New 3DS game.
Does marketing play a role in the technical exclusivity of a game? Much is made of the advertising arrangements for Destiny and Battlefront on PS4. Sometimes such games are treated like Sony exclusives, even though they are also released on other platforms. So does this argument apply to a first-party trying to phase out older hardware?
I would say that if a game was backwards compatible with the original Gameboy, then it wasn't exclusive to anything but Nintendo. It was a "Nintendo" exclusive.
Come on now, that's cheating. This is a yes or no question.