Honestly, there’s still some core features of the Nintendo Switch that are more unclear now than they were 3 weeks ago. There’s nothing more unclear than how Nintendo is going to handle online/matchmaking/voice chat.
Now, an official Nintendo Switch diagram has detailed that the headphone jack will be compatible with headphones, microphones and tablets”
The specific line says: “For connecting commercially available headphones, microphones and headsets”
Now, this could just mean that they are compatible but the system won’t have the functionality built in to voice chat, but it seems like an incredibly odd thing to note if you’ll need to plug a microphone/headset into your smartphone to voice chat.