Tomorrow Children, loved that game but it got killed off not even a year in, main issue was it wasn't meant to be a free 2 play game and Sony making it into one last minute caused the devs a lot of issues. Would love to see it brought back with a single player mode and stuff they didn't get to add last time such as mech battles.
Sly 5, sucker for 3D platformers and the way Sly 4 ended on a cliffhanger makes me want one more to wrap things up.
Ape Escape 4, AE is a great series and hasn't had a game since that awful motion control game for the PS3 back in 2011, Sony keeps using AE for promotion so maybe some hope still there.
Jak 4, doubt ND would want to go back to Jak nor would I want them to after the Jak 4 they had planned before canceling to make the Last of Us, however if Sony could find the right dev think it would be a good series to bring back.
A real Beyond Good and Evil 2, not a prequel, none of that always online shit, just single player and Jade as the MC.
Pikmin 4, what's the hold up nintendo?
Croc remakes, Croc on the PS1 plays like shit and has not aged well, but the level design was alright and music was great, feel like a remake that at least makes it play like a more modern game would be great.
Metal Gear Rising 2, feel like Metal Gear Solid should stay dead without Kojima but Rising that shit can work without him easily, just need Platinum games.