There's too many systems for developers to support anyway.
Next year it will be PS4 + 720 + PC + iOS + Android + Wii U + PS3 + 360 as very active platforms for Western devs.
No Western dev is going to put a major team on a 3DS or Vita project IMO.
Japanese devs will support 3DS by default.
Vita is left in no man's land.







