Before you lay the hate on this, what I want to talk about is how Halo 5 can appeal to casual audiences, and more prominently - CoD fans WITHOUT compromising it’s skill gap and that core gameplay feel that Halo has had from the beginning.
Now the first way is through some modifications to the single-player:
This first one concerns the A.I.in the campaign as well as Warzone. What they should do with the A.I., mostly with the elites, the promethean knights and the new promethean enemies, is implement player-like strafing on the higher difficulties… Now what this can do is teach the player the basic movements and aiming techniques found in the multiplayer, let him do trial and error, without that impacting his stats and reputation.
Such a system can be implemented by analyzing strafing and aiming patterns from gameplay footages and recorded data during the betas, whether it’s Halo 5 or even Halo 3, because I’m sure 343i has access to that data, even if it is archived. So for instance in heroic you have your average top-level player, who has developed that strafe skill, has very decent aim, and has a very good idea how to use his environment(i.e. knows all the maps, but a given A.I bot only needs to know his own area of the campaign/Warzone map). And legendary can be at the level of an HCS player. Here you can add some hive mind algorithms, to simulate team coordination, when faced against a bigger group of A.I enemies.
Another thing that can be done in the single player and is a lot less far fetched, is let A.I(which isn’t flood) use Human weapons. That way you can get a pretty good idea what it’s like to get killed by a BR before going through an FFA BR fight on Midship, ending the fight with a score of 2/15, the 2 being some unlucky -Yoinks!- who got temporarily disconnected after spawning, but I digress. Now you can argue that there is generally no reason for either the elites nor the promethean knights to use a BR or an SMG and there never has been, but in the entire original Halo trilogy, you had a lot of situations, where covenant are fighting flood, you could have them run out of energy in their plasma weapons or needlers etc. and have them pick up an SMG nearby, or a BR, then they start shooting at you with it. This makes for a perfect environment in which you can learn the fundamentals of BR fights, you know, minding your aim, making sure the entire burst is on target, trying to avoid a full burst if not the entire one etc. This is a small gesture, which can help a more casual player get introduced to the Halo multiplayer in a less hostile manner.
I was going to talk about bringing back load-outs in Halo multiplayer BUT restricting their presence to specific game modes or maps, maybe put it in a variation of BTB, but then Warzone happened so nvm. But I think the Req system should be put in one or 2 game modes in arena BTB ONLY. This way, those with a preference to CoD could be attracted to playing Halo more often as they can have the equivalent of load-outs in a non-Warzone game mode, because the addition of AI on a multiplayer map is quite awesome, but not everyone will like it, especially if they prefer playing more often with the req system
I know the first idea with the A.I. is very far fetched, and most likely impossible to be implemented into the A.I. system so late in development, but it could be considered for Halo 6 or future titles.