I think that it would be good for the story if the flood came back because if youve watched halo legends you would know that it wouldnt be the first time they survived the activation of the halo arrays, and if the prometheans are in halo 5 then they will need to bring the flood back so we can see them fight eachother. also 343 industries have improved the graphics so vastly that they just have to show us the flood at some stage in the saga.
It would be good if the arbiter came back too because he has been a fairly major part of the first halo saga and 343 just wouldnt do the saga justice if they didnt include him in at least one of their games. Also the idea of the storm covenant causing a civil war isnt so far fetched, after all the arbiter managed it in halo 2 and 3. and it would be good to see the arbiter with the new graphics, i think it would be kick ass.
If they dont bring cortana back i will lose my mind and possibly never play halo again. she was my favourite character of all time from the very begining to the end, no questions asked. in my opinion if 343 dont bring her back they are making the biggest mistake made in gaming history, EVER, NO EXAGGERATION. Killing off one of the main protagonists in the first game of a triology was a big mistake and they need to rectify that mistake. Cheif needs cortana more than he needs anything, you cannot have one without the other.
all of these things are ABSOLUTELY ESSENTIAL FOR THE STORY. The Reclaimer Triology is suppose dto be about cheif facing his destiny... We can probably assume that the flood have somehting to do with that destiny. The arbiter was like a best friend to the cheif. and arbiter helped cheif out of a lot of sticky situations in halo 3. cheif needs the arbiter in a similar way to that which he needs cortana. All of these things literally NEED to be put into the triology.
