Nintendo can play form-factor SKUs whenever they want as long as they but play same Nx portable line-up. Think of Nx portable like the GBA and other form-factor SKUs like a GameCube sans optical disc drive plus GameBoyAdvance player attached on the base of it. I know Nintendo was forced into this position in order to have CapCom and Level-5 camping Nintendo3Ds pastures, but they are already defacto a single platform company. Just a couple of partnership title per generation can be developped without portable resources in the core, this turn was the case of Xenoblade Cross and FE#, plus Aounuma team that fiercely took apart Zelda console from Zelda portable, against itself, against the market, against living in the confort zone, against profitability.