This is Halo 5-Microsoft confirms

Games Halo 5: Guardians
1

People are wondering if the teaser trailer we saw was for Halo 5 or a story in between Halo 4 and Halo 5. Well I was on facebook, and went on Xbox’s page, which said this, "The Halo universe has expanded to include the Xbox E3 2013 Media Briefing. Watch the trailer for Halo 5, coming to Xbox One. Halo on Xbox One: Official E3 Trailer - YouTube

ESRB Rating: RATING PENDING". This means what we saw is indeed Halo 5!!!

2

Edit: never mind. Mods are on top of it today.

But yes, multiple sources have confirmed it.