Vita just needs a constant stream of games. Aside from the mighty triumvirate, 3DS is getting or has already gotten
Kid Icarus
Kingdom Hearts
Theater Heaven
RE:R
DQ:Slime
Heroes of Ruin
Love+
Harvest Moon
Fire Emblem
Mario Tennis
Rune Factory
Etrian Odyssey IV
That's just for the first half of the year too. We know we're going to get at least Luigi's Mansion, Bravely Default, and Paper Mario in the second half. None of those, with the possible exception of Kingdom Hearts, are going to set the charts on fire or are likely to break a million units in Japan, but they represent a really steady stream of mid to high quality titles that people want. Each of those games will sell at least a few people a console. Then there are the big hitters this year like Animal Crossing, MH4, a possible new 2D mario, and whatever else is announced at E3.
If at any point in its lifetime the Vita can secure a steady stream of mid tier games, I'm absolutely confident it can find a good deal of success. A handful of games here and there just isn't going to cut it. Sony really needs to convince people on the 9th that they've got major plans for a constant stream of games. They really, really need to pour it on.