Master Chief in Call of Duty?!

Sledgehammer Games at one point had plans for a large scale Halo cross over into Modern Warefare 3 according to CoD leaker TheGhostofHope. Hope said that the collaboration was set to include various maps from the Halo franchise as multiplayer maps in Call of Duty Modern Warfare 3. Last November it was rumored Halo could be coming to Black Ops 6 though much like with Modern Warfare 3 nothing has coming of the rumors. Is it time for the Chief to branch out?