There's supposed to be a good TPS coming soon. It's called Ironfall. If it does well, maybe we'll get more.
Personally, I own a Vita and I just don't know if FPS are a good fit for handhelds anymore. I used to buy them for the DS just to see if it could be done but the novelty has worn off, now. On Vita, even if you get an FPS that works well, you have to have Wi Fi to play online and if you're in a place with good Wi Fi, there's a pretty good chance you're in a place with a home console. Why play online on a portable if you have a console?