I think Nintendo's valuables are not in hardware (anyone can build a hand-held console these days) but in the huge library of very famous games.

If 3DS has lost the game, nothing stops Nintendo from re-releasing some of popular old games for iPhone (perhaps developing a descent emulator for iOS) and keep writing more excellent games in future.

Example: iD made another stash of green from Apple's app store when Carmack released Wolfenstein 3D for iPhone.