Why aren't they reviving Halo 3?

Bungie probably couldn't think of a new game, because they ended Halo 3 soo perfectly. The flood was destroyed, the covenant was defeated, the Halo rings were destroyed, and there was peace between the humans and Elites. What else could they do? So they thought it would be cool to have you play in a group of spartans, so they had to make it before Halo 1 because in Halo 1 Master Chief was the only spartan left, which means there would be no other spartan but him. Many people don't think it lines up with the story at all, but at the last level you bring Cortana to the Pillar of Autum(idk how to spell it and idc) then you protect it while it takes off, and durring one of the end cut-scenes you can see the master chief on the Pillar of Autum. They put it on planet Reach so it would make sence because some people argue that "why do they have more advanced weapons in Halo Reach than Halo 3 if Halo Reach was far before Halo 3?" but planet Reach was a weapons and supply making planet, so Noble Team had the ability to use new prototypes that were only on planet Reach, and not available to anyone else after the planet got gled. Also in every game since Halo 2 somewhere in the campain people had mentioned something about planet Reach, like in Halo ODST where many people had said "oh no! this is gonna be like Reach all over again!" which would make sense because many of the ODST's in Halo ODST were on planet Reach when it was getting taken over and gled. Like I was saying before though, didn't make Halo 4 probably because there was no way to make a new story, but I think Microsoft will find a way(they bought the contract of the rights to make halo games) and Halo 3 set it up so they could so all they need to do it take it from there.