The PS Vita already has the option of using a 3G network. I don't see why they couldn't make plans (like a phone) and add calling and texting to future handhelds.
Hopefully, people will do all of their calling, messaging, etc. through programs like Skype and Facebook in the future anyways. (The PS Vita can run those programs.)
Also, it seems like a longshot at the moment but if all of those features could be put into one program with live updates to your device, any mobile device with internet access could be using a universal messaging and calling system.
I'm assuming audio, but a visual headset is probably possible for the Wii U.
Also, kinda off topic, but I'd recommend Sony's official PS3 headset (Not the Bluetooth one.).
It's called, 'Sony Wireless Stereo Headset'.
I'd only recommend it if you're willing to pay a hundred dollars though.