Legend of Dragoon. Easily the best non-Final Fantasy RPG in the PS1 era, it had the perfect ending for a "the next generation" game.
Megaman X. I know the series was pretty much dead after X-5, (X-8 wasn't bad) but come on... it's long overdue.
Chrono Trigger. Chrono Cross was easily the third best non-Final Fantasy RPG in the PS1 era. The series could use a third game, maybe.
Metroid. I mean it's been what, 5 years since Prime 3? Isn't it about time for a new sequel? And how about giving her some characterization this time? You know, something a little more to do than run and shoot things. I mean it's not like you're going to turn Samus into some kind of rape/abuse victim, right?
Kingdom Hearts. Ok, enough of this prequel crap, SquareEnix and Disney. Kingdom Hearts 3. Make it happen. (not that the prequel stuff wasn't good, but come on...)
StarFox. Wow, a lot of Nintendo series, huh? StarFox hasn't had a proper sequel in two generations. I want to shoot stuff in space and do barrel rolls!
Star Wars: Knights of the Old Republic. No, your upcoming MMO does NOT count as a sequel, Bioware. I wanted KotOR 3. Lets wrap up some stories before you start retconning everything, shall we?