There are a lot of games I would like to see, either conceptually, or specifically.
Some specific games I would like to see:
Baldur's Gate: Dark Alliance 3
Breath of Fire VI
Colony Wars IV
Geneforge VI
Icewind Dale III (but not if they use the awful 4th edition setting)
Lords of Magic II
Master of Magic II
Master of Orion IV
Medievil III
Neverwinter Nights III (but not if they use the awful 4th edition setting)
Jade Empire II
Jagged Alliance III (the recent one doesn't count)
Jedi Academy II
Jupiter: The Nexus Incident II
Knights of the Old Republic III (not some MMO cashgrab either, a proper sequel)
Shogo II
Star Wars Battlefront III
Star Wars Empire at War II
Wheel of Time II
Less Specifically:
A Babylon 5 game, either and rpg or a flight simulator in the vein of wing commander, colony wars, freespace, etc. Flying starfuries, or a Minbari Nial fighter would be awesome, and Babylon 5 was always a bit deeper than some other similar pieces of Sci-fi such as Mass Effect, so I think it could make a good rpg as well.
A Stargate rpg. You could play as one of the assorted non-SG-1 teams that were mentioned and soemtimes shown in the show. Preferably in the Goa'Uld period before the Wraiths, Replicators, and Ori took over, when the Goa'uld were still somewhat intimidating and dangerous.
A Star Trek RPG, preferably set in the period of time between Wrath of Khan and Next generations, when technobabble was a bit less prominant, there were no lazy holodeck episodes, people didn't bring their kids along on warships, Klingons were not yet 'angry space vikings' and starfleet had those spiffy red uniforms. There would be less alien species bloat, and the game coudl focus on the interactions between the Klingons, federation, and Romulans.
A game similar to the Total War games, for Warhammer or Warhammer 40k (I am aware there is a Warhammer Fantasy mod for Medievil II) This one might actually happen
A Warhammer Fantasy or Warhammer 40k rpg. The possibilities are endless!
An Elder Scrolls game that has a setting half as original or immersive as Morrowind.
An rpg where the player works for the big, bad Sauron stand in instead of opposing him. Isntead of the usual Dwarf/Elf/Human selection, you get some more exotic evil options such as orc/demon/beastman/ringwraith/vampire etc. Instead of running around the countryside tryign to rally the free peoples or recovering magic artifacts etc, you would be working to undermine the forces of good etc.
An RPG set in the world of the Lone Wolf choose your own adventure books. I loved those when I was a kid, so much that when I took to modding dwarf fortress, one of the races I modded in was based off of Darklord Gnaag.
Someone earlier mentioned a Harry Potter RPG, where the player played as a player-created student instead of Harry etc. I think this would be great, I love the concept of a Mage's College/school/guild etc. The Elder Scrolls series had these, but they were always rather shallow, and you could easily go from apprentice to archmage in the relative blink of an eye. An entire game focused on a vast mage tower, where the palyer learns spells, deals with intrigue, makes allies and enemies, before having to deal with an external (or internal) threat to them and the school would be pretty fun I think. Harry Potter's Hogwarts or the White Tower from the Wheel of Time books would be nice canidates for that, or a generic setting could be used.
There are a lot of ideas for games I would like to see. I have had a lot of time to think about them because there have been very few games in the past few years that have earned my interest. They all seem kinda samey/mass-market and phoned in of late.