The aim will indeed be to restore Humanity to its original state and finishing the work of killing of the Precursor(s) and the Flood (yes they will be back). I expect some kind of voyage/quest to ancient human planets/ruins instead of forerunner ones.
I'm intrigued with where they go next, now that Master Chief is a Reclaimer Human. I mean, after that, surely the next step is finding the Mantle and restoring all of humanity to its original state? And then going to hunt the Old Enemy? And surely, somewhere along the way, there has to be at least one trans-sentient being?