Just some things about the release dates for Vita games in the in the OP:
- Playstation All-Stars is releasing on January 31st in Japan
- Senran Kagura, Phantasy Star Online 2 & Ninja Gaiden Sigma 2 Plus are releasing on 28th February in Japan.
- Soul Sacrifice & Tales of Hearts R are releasing on March 7th in Japan.
- One Piece Pirate Warriors 2 is releasing on March 20th in Japan.
- Dead or Alive 5 Plus is releasing on March 22nd in Japan.
- Ratchet & Clank: Full Frontal Assault hasn't been given a firm release date for Vita yet.
There's also some smaller stuff like Demon Gaze & Monster Monpiece in Japan on January 24th, Muramasa on March 28th in Japan or Atelier Meruru Plus on March 30th. None of them are "major" releases as you've put in the title though, so it's up to you if you include them or not. All release dates are from amazon.jp or Siliconera, wherever you're getting the release dates from seems a bit out of date/random guesswork.
Have fun tracking! (Also, 8 million Vita seems like a bit of a pipe dream that no-one has realistically predicted. But if you think it'll come true, then fair enough :P)