This is a theory I had on how they would incorporate allies into this next Halo game since by the trailer it looks like Master Chief won’t be around the UNSC much. So, what if while trying to accomplish his missions he met up with some elites throughout the game and grouped with them since he saw it as good cover while in hiding.
I think an optimal storyline would be if Halo 5 started out a year or so after the events of Halo 4 and we pick off with Master Chief already grouped with the elites. Also if the elites knew some English due to experience in the war against humans several years back, they were able to teach Master Chief how to speak Sangheli, and taught him how fighting tactics like an elite.
If they showed him speaking just one line in the elites language it would really make for something interesting.