I find it funny that huge franchises like Halo and Gears of war branch out to beverages, comics, novels and potentially movies but truly interesting games in the universe are foregone in favor of playing it safe. Halo Wars was interesting, but really nothing new was brought to the genre and the game itself was fairly vanilla. Here is what I want:
Gears of War tactical strategy game – Turn/real time hybrid with Delta infiltrating the enemy using tactics instead of third person action. You could deploy in a pre-planning phase and the action for the turn is real time (no turn versus turn, you tune the reactions and readiness of your gears). There could be dozens of mission types, environments and upgrades for the Gears. hell Carmine could even be in this one.
Halo action RPG – Think Mass Effect with the huge allure of the Halo Universe. Start with a new Spartan and progress through a conflict that results in him achieving glory. hell this could even be Master Chiefs origin story…
StarCraft action RPG – Hell we almost had Ghost, instead as described above start with a newly created Ghost that progresses through her adventure meeting companions gaining allies and eventually stopping a galaxy spanning conflict. The richness of units and characters gives this a huge base to draw from when creating the environments and scenarios.
There are many options out there and I would love to see more developers get out of the comfort zone for franchises and spread their wings a bit.