Sony's plan for the Vita over seas is to make it a PS4 accessory, the only reason they support in Japan is it's the only keeping their consoles relevant over their. Most of the games on the Vita appeal to the Japanese demographic, which isn't a bad thing, when they get ported over seas(if they even do that) the game gets no advertisement, and is generally not what most people want here.
Also when was the last time anyone saw a Vita commercial!