After it was revealed that Microsoft intended to shut down Ensemble Studios, many wondered where the company was going after completing Halo Wars. While that project will indeed see the light of day, it has been revealed that Ensemble was also planning and working on a Halo MMO game. Little details aside from some early development prototypes were discovered, though it was revealed that the game itself was put to rest sometime last year. This could indicate that Ensemble was aware of the impending shutdown for some time in advance.
They still are on track to complete Halo Wars, and overall the Halo series is definitely not over – Microsoft has admitted that other companies they work with will be developing Halo-sourced projects in the future.