I think that if handhelds survive, they'll become somewhat of a "niche" market - they are already that, with the exception of Pokemon.
In the past, handhelds served the purpose of "close-enough" gaming experience: you want to play something, you're not home, you turn on you GameBoy and have fun.
But now, portable consoles are quite expensive, have a ridiculous battery life, are too big to fit comfortably on a pocket... smartphones are a much better option for this "almost-a-videogame" experience.
People who still buy and enjoy handhelds are mostly people who really like video games, like you and me. We buy a 3DS because it's the only place we can play Bravely Default, and a Vita so that we can play Gravity Rush. No more casuals (dat Nintendogs and Brain Age sales, for example). Maybe the market can sustain itself based only on this public. Sony seems pretty satisfied with the current niche condition of the Vita at least.












