Oblivion, Fallout 3, and Fallout New Vegas could use a 64-bit version. Even if they change absolutely nothing else about those games, that alone would be a major improvement, as they are very prone to crashing from running out of address space, especially if you have graphics mods installed.
Final Fantasy 9. It's my favourite in the series, and it's gotten lots of rereleases in its original form. But it would be nice if it got a more polished updated remaster.
Though I would be afraid of how modern Square sensibilities might change the pretty iconic character designs.
Early BioWare stuff. Specifically KOTOR (don't know what's going on with that remake, but doesn't seem to be going anywhere right now), KOTOR II (yes, I know it's Obsidian, but still), and Jade Empire. Probably Dragon Age: Origins as well.
Since they're already doing it, it's probably a useless mention, but Splinter Cell needed it, especially for PC.
Star Wars: The Force Unleashed and the Kyle Katarn Jedi games could probably do with a touch-up as well. But they're "not canon", so that's not happening.
Maybe also the original Deus Ex and/or Thief.
I expect System Shock 2 might get one in a few years, although it isn't as desperately needed as the original was.
There are a bunch of old Sega IPs I'd love to see get a modern treatment. Alex Kidd. Space Harrier. Shinobi. Wonder Boy in Monster Land got the proper treatment a few years back with a gorgeous remake and a pseudo-sequel.
.hack IMOQ (I was coping so hard after GU got a remaster but still nothing)
Dragon age origins
Digimon world 3. There have been two reboots/reimaginings of digimon world 1 (re digitized decode, and next order), but never anything about world 2 and 3.
C&C: Tiberian Sun and the Firestorm expansion. I wasn't the biggest fan of the original C&C, but picked up the remaster to show my support in the hopes that Tiberian Sun would get the treatment. Unfortunately, that doesn't seem to be happening as far as I've seen.
I really enjoyed Sim Earth as a kid. Just give me an entire planet operating on a geological scale as a sort of "virtual terrarium", and I'll be happy.
More a remake from the bottom up than just a remaster, but 1st person 3d Fallout and Fallout 2.
It's probably impossible due to rights issues and the like and would definitely piss off purists, but it would introduce a new generation to the origin of the series, the game that us olds first fell in love with.
It would also give us the opportunity to experience them anew with increased immersion and immedience as we wait for 5 to be released some time in the middle of the 2030s if even then..
Icewind Dale 2 need a remaster / EE edition. I remember reading somewhere that the source code was lost. Same issue with HOMM3 extensions that why there is no HD edition of the full game and why GOG version is still the best.
Good old Revolt. It'll be awesome with a remake of the game with the similar feel, realistic driving characteristics and challenging gameplay that's actually fun and difficult to master. I'd love a hyper realistic version of an RC car game just like revolt was back when it launched.
Jak II (and probably the others after it but I haven't gotten to them yet so can't say for sure). Not Precursor Legacy though, it's perfect and nobody can tell me otherwise
Edit: jk I forgot Precursor Legacy didn't have subtitles, it could do with those.
Half Life 1 (and 2 at this point, tbh)
Actually fuck it let's just re-do all the Valve Source FPS. TAKE MY MONEY
Roller Coaster Tycoon 1 would be an awesome candidate for an AOE Definitive Edition style remake where the mechanics are virtually unchanged but it's given a 3D graphics overhaul with unfixed zoom levels
Tron 2.0 but it'll never happen because it's a split timeline from Tron Legacy :[
Matrix Path of Neo. I loved that game so much and the last time I tried emulating it was so bad. I was completely hyped at that recent tech demo until I realized that was all it would be.
I know I’m in a minority but DK64! I loved that game as a kid. Maybe it was because my game library was quite small growing up but I spent hours and hours during summer vacation with the DK Crew
I'll give them points for fixing the technical issues. But, IMO, slapping some textures (that breaks the original atmosphere) isn't good enough. It would've been amazing to have Demon Ruins + Lost Izalith fixed.
But to be realistic this was nothing more than a cash grab; minimal effort. Which I can't necessarily blame as that's the whole point of people doing anything. People gotta eat.