I just hope they restore CE style cutscene manipulation, where you could have active enemy AI in cutscenes. In H2 and H3, often enemies had to be killed for the cutscene to start and they would end up being deleted even if it wasn't necessary to kill them to start the cutscene. Furthermore, only allies would appear in cutscenes, more so in H2 (like the end cutscenes on Cairo Station, Uprising, and Great Journey) than in H3 (both Arby and Johnson could be killed before starting it in most cases but that's about it).
There was only 1 cutscene in H3 that allowed active enemy AI but it was at the top of the third tower and you could only bring 1 enemy up the elevator due to AI wanting to get off the elevator (Bungie probably didn't want players pushing Elites up the elevator to make the upstairs battle more easier but perhaps they didn't want players having fun with the cutscene). I have managed to get an AI battle going on upstairs during the cutscene (in CE, I believe you could only have this at the Goldie cutscene on Silent Cartographer if you left marines there) in addition to uncovering that the bipeds in most if not all cutscenes are tangible.