Since they have a system with enough power to emulate probably up to N64 - they have a nice joker at hand.
Whenever they experience a bad business year or might miss expectations on something, they could just wip out a Gameboy, SNES, N64, GBC, GBA Classic Mini. They have the tech already, they just need a different mold and an emulator.
I wouldn't expect this to become a yearly thing though, they want to/have to focus on the Switch next year.
Those sales are pretty awesome though. If they manage to keep stock up, they'll manage to sell several (2?) Million this year worldwide.