Changed op a bit, I added the release dates of some upcoming big PS Vita games. If you know more release dates of other upcoming PS Vita games, feel free to post them here! :)
If Sony plays the cards right they can make Vita a perfect option for developers at least untill 2019. Especially now that developers are pushing hard for PS4/PSVita releases, Sony should lower the price or introduce a new model along a big game (Heroes 2, Saga or Toukiden 2) but they should do it before the release of big PS4 games or a PS4 slim model in order to not cut the PS4 hype.