The Legacy of Kain. I want a proper instalment that continues the story, not some multiplayer rubbish set in the same world, thank you, Square Enix. Kain is such an interesting and complex anti-hero, and Defiance BEGS for a sequel. Even if it's an alternate timeline like Blood Omen 2, I want to see more of this world. How likely is this? Probably not very likely, although I'm going to hope for an HD remaster of some sort in the future...
We're long overdue a MediEvil 3. I loved the clever British humour in the first two games, and with Sir Dan in PlayStation All Stars I was hoping they'd bring him back for another game on the PS4...I'm still waiting and hoping here. The market is filled with poor quality platformers, I think there is room for a good one to make a comeback. This had better be likely.
I think I'd cry tears of joy if they made another Final Fantasy Tactics game...or just another game set in Ivalice; it doesn't have to be Tactics. Ivalice is such a rich and detailed world, and there is still plenty they could do with it. New Ivalice game now, please! Highly unlikely, I suppose...
I'm on the fence with Metroid. I'd be quite happy to see either first-person or side-scrolling styles return, but I don't want the story to be anything like Other M. Other M was an absolute disgrace, and if it is any indication of what they're going to do to Samus' character in the future, I never want to see another Metroid game made, ever. No matter how good the gameplay may be, it wouldn't excuse it. If they're going to make more Metroid, I don't care what it is as long as it's a PROPER Metroid game. I don't know how likely this is. I think it's almost guaranteed they'll make a new Metroid game at some stage, but whether or not it'll be worthy of the franchise is another matter entirely...
I'd also like another game set in the same timeline as Drakengard and NieR. A sequel to NieR would be quite interesting, as they've covered pre-Drakengard with Drakengard 3, but the beautiful thing about Drakengard is that it has multiple timelines. Granted, most of them end with the world ending, but they could still make another game based off one of its other endings. But a new game set in this world means more bloody combat, insane characters, and peerless music. I can't see how this could possibly be a bad thing. This could be possible; despite negative reviews the two games have something of a cult following.
Another Castlevania game would be nice, too. I know they're done with Lords of Shadow for now, but I'm excited to see where they'll go next with the franchise. Another side-scrolling Metroidvania would be preferable to a 3D action-adventure game, but I'd be happy with either one; I just don't want the series to fall into obscurity. I expect it will make a comeback at some stage, although probably on PS4 and Xbone, and maybe Vita. Vita would be lovely.
Also, Star Ocean. I'm quite irritated we don't have a Star Ocean 5 announced for PS4 (and Vita, please!) yet. The PS4 is starved for JRPGs, and asides from Till the End of Time, I've actually really enjoyed the games; they have more engaging and fluid combat than the Tales series, and the futuristic story is appealing. Just...no more battle trophies, please. I despair at ever getting the Platinum for the fourth game. I don't know how likely this is...I doubt it'll come for quite a while; there is an obscene gap between release dates for Star Ocean games.
Valkyrie Profile making a comeback would be nice as well. Hrist still doesn't have her own game, and she's the most interesting of the three sisters, being a cold-hearted bitch. More Valkyrie Profile means more Lezard Valeth as well, and that can't be a bad thing. I hold out very little hope for this, though.
This is highly unlikely to the point that it isn't worth mentioning, but I'm going to say it anyway: I want a fourth Arland game. I got so attached to the cast I didn't want it to end with Meruru, and I want to go back. I'm so annoyed that they've decided to have an Atelier Astrid mode in Rorona on the 3DS; they could have made a full prequel out of that! I want more. MORE.