It would be cool if we get a continuation of the Chief's story in DLC without having to wait for the next game. I think this is the first Halo game that should really have it - they can't just keep making 5 hour, 8 mission campaigns and hope to tell a grand, memorable story.
Not to mention there is a gap of time between the ending and Spartan Ops' story. What is the Chief doing in this time?
I want to see what happens, and I don't want to wait for Halo 5.