But the handheld sales are a lot more stable, with the 3DS selling almost as much as the GBA and the DS selling more than the GameBoy.
Nintendo now only has 1 console anymore, which means they can develop more games for it than for any of their other consoles/handhelds.
Nope. Nintendo still has the 3DS as well.
When they stop producing anything for it, we'll know if the strategy they have for the Switch (one console bringing both of their markets as one) will pay off.