People often tell me this idea is brilliant: remake Star Wars: Republic Commando.
Instead of making a sequel, which fans have LONG awaited, just extend the original game by a couple more planets (that would be enough to wrap up the narrative, most likely, though they could add as many as they want). You could do it in the same way that was done for Halo: CE Anniversary, where they updated all the textures and you could press a button to switch between graphics. The engine was wonderful; they wouldn't really have to change a damn thing. Jedi and rogue clone troopers would be new enemy types - prolonging the original's somewhat short campaign - as the Commandos are forced to hunt them down in accordance with protocol, creating an AWESOME conflict. Perhaps so much so that the squad would break apart (i.e., Fixer, being devoted to his duty as a soldier, and sticking by the rules, wouldn't really think of disobeying orders to kill Jedi, whereas someone like Scorch, who is brash and less concerned with orders from higher up the chain, would only be thinking of Sev's safe return. It would be up to you, the player, to decide which route you take. If you stay with the Republic, you and Fixer go on a killing spree, essentially, supposedly "doing the right thing" by obeying and playing by the rules, and forcing Scorch to break away to search for Sev on his own. Or if you go rogue with Scorch, Fixer would be the one to leave, and you try to find your brother in the dense forests of Kashyyyk, possibly even on the forest floor, where even Wookiees fear to tread).
New weapons would be a possibility, though their inclusion wouldn't be necessary.
They could also make the multiplayer... you know... not suck. They would have all the time in the world to make better maps, and improve upon the character customization and such. Additionally, there's no reason why they couldn't incorporate the squad commands into the multiplayer. One player signals for someone to take up a sniping position, which appears on every player of the same team's HUD, while another takes point. It could add levels upon levels of strategy to a stagnant, dull-as-dishwater FPS multiplayer scene. Being able to issue commands in complex maps would be a thing of beauty. Players wouldn't have to listen either, perhaps because they have a better plan, they're gonna lone-wolf stealth-kill everybody, or they're just a douche, it doesn't matter. All these factors decide who wins (usually being the most tactile, clever, cooperative team). Doors to enemy bases (or good sniping positions or whatever else) could be hackable as well, so you could have technicians keeping everything running smoothly, silently, and efficiently - like Fixer. And if you're gonna do THAT, why not have the ability to blow doors up with charges? Of course, that would alert enemies to your presence (on the minimap), so watch out... Things like dormant droids in the map could be rewired to fight for your side or provide a clever distraction... or rigged with explosives and sent to creep up behind people (Creepers... outside of Minecraft? MY GOD.)
The game had such great controls, and really got the whole squad-command thing down. The physics were awesome, the enemies were tactical (maybe not the droids, so much, but what they lacked in AI, they made up for in numbers and firepower), the story was great, and you really felt like a commando. If they did do a sequel, most likely it would suffer from either being dumbed down or having feature creep ("Hey, they liked all THESE features... what if we add THESE ones too!?"). The game would probably be short, again, as they explore the narrative I described above which could be taken care of in about three planets. The engine would definitely be new, so the game just wouldn't FEEL the same, no matter what. And the multiplayer would probably become the main focus, as is the way of shooters these days, rather than the singleplayer. I want them to IMPROVE the multiplayer, not make it the focal point.
But... methinks I'm being too hopeful.