I know, I know, it was called Ghost, but my idea is different.
How about a Console game in which play from a third person view of the whole starcraft saga. You can play as multiple characters, such as Raynor, Kerrigan, Zeratul, Tassadar and others. You experience the world through their view points. This means that we can play as Tassadar or Fenix on Auir prior to and during the Zerg Invasion. Or play as Kerrigan before she met Raynor as well as in her infested form.
The story mode itself would encompass many of the novels, such as Queen of Blades. As well as new material, in fact, the story itself doesn't necessarily have to follow the pc version to a sync. It could branch out, have its own paths, even its own endings.
A really good example would be if another race was added. In my mind, it would be a superhuman race called the Sentinials. These are humans that drifted from the main fleet and crash landed on a distant planet, that teemed with vespene gas to the point where all the food supply on the planet mutated the humans. Now these guys are larger than normal humans, have incredible strength, speed, and even psionic powers. These guys don't have to show up in the first game but in a sequel perhaps. This is just an example of my idea of the story.
In terms of the gameplay, that would depend on the person you play. If as Raynor, then it'd be more of a Resident Evil 4/5/Red Faction: Guerilla type of play that is/can be both squad-based in certain situations and during huge battles, a free for all. It would involve shooting, melee, and context-based attacks such as those in RE4/5 or God of War. When the situation calls for it, you can pilot vehicles, and if present, or even off map, call down air strikes, reinforcements, hell, you can even set up points for your base and decide what to create or have a preset starting base and seek out resources or points to fund your operations. A great example of this is 1998's Battlezone.
If you play as Kerrigan, it would be two types of gameplay. The first would be a more stealth oriented type, like Starcraft: Ghost and when Kerrigan is transformed, it becomes more of a button masher or God of War/Dynasty Warriors gamesplay. She would be able to control her own brood, making both base building decisions as well as upgrades to herself and her brood.
As the Protoss, it would be God of War/Dynasty Warriors style with both combat as well as puzzle solving. However, if you play as Fenix in his Dragoon form, it would be a 3rd person shooter, though you can switch to a first person view as with all shooter based characters. Though a first person view for non-shooter based characters is possible. Base Building and resource acquisition similar to Battlezone again.
As for Multiplayer, the foundation of all Blizzard Games, Savage: New Earth is a great starting point. The idea of having a commander from the top and grunts on the ground taking orders maintains the Starcraft-ness. AI computers or players can act as the various units on the field. Players can create maps where there is a certain number of players playing as units and the rest as computers. A queue line can be set up for waiting player to opt-in. Players can play as any of the various units, though the selection depends on units available at the time. An option can be made available where players can skip on the next available unit and wait for units they prefer.
As for a Map Editor, a mouse/keyboard set-up can be used as well as a controller for ease of use.
In fact, an option can be made where if a person has both a mouse/keyboard and a controller hooked, they can use both during game play, both online and offline. Aw, hell, why don't we just port this thing to the PC too and finally have PC gamers and console gamers on the same server :)
But seriously, this is a good concept, though of course it's the execution that matters. Hopefully I gave you guys some ideas to pitch. Keep up the awesome work.