First of all, procedurally generating each building's layout, and map layout is an absolutely brilliant idea. I've seen this before in Due Process, as that extra layer of uncertainty will really go along way in making the game more tense and unique every time we play. Though, I'm worried that there will only be so many configurations that can be generated, like how in No Mans Sky you have all sorts of biomes generated on different planets at random, but they all end up feeling the same after playing for a while. So please make this procedural generation more dynamic in that we truly won't know what to expect (take a look at Due Process for inspiration).
My second concern is this with the multiplayer. I understand that there's going to be CO-OP in this game and I'm all for that, but I bet that a PVP gamemode could also work well (I mention PVP because there's a huge market for it, and could bring more players into this game). A simple PVP gamemode could be something like this:
One team has a high value target (HVT) as hostage, and must hide them in one of the buildings in the neighbourhood. They then must set up an ambush to prevent the enemy team from securing the hostage. The other team would then have to attempt to save the hostage (or equivalent, such as intelligence) and head back to the exfiltration point. This idea is inspired by Ground Branch, so if you'd like you can have a look there too. Basically, the bottom line here is that PVP could work really well this this kind of game, even if it is mainly singleplayer or CO-OP focused. Something simple could really go a long way.
Also, I know that you said players would never play as an insurgent, but please reconsider this for the multiplayer aspect.
Third, DO NOT make this a run and gun Call of Duty type game. I know that you guys probably aren't going to do this, as the gameplay trailer seems to show off slower and more tactical gameplay, but I just want to mention this to be sure. Slower gameplay means greater tension between engagements and will absolutely make or break the experience that this game is trying to accomplish. Games that pull this off well are Ground Branch and Escape From Tarkov.
Finally, just some nitpicky things that I noticed in the trailer. These are very minor details, but for the sake of realism and to calm my OCD, I thought I'd mention them:
- Use the bolt catch and not the charging handle! I noticed in the trailer that the player's reloading animation involved him pulling back the charging handle, when marines have been trained to hit the bolt catch on the side of put a new round in the chamber. For a game trying to be realistic this bothered me a little bit.
- Make the bullets invisible in the air. I noticed that the bullets were visible when flying through the air towards their target, when bullets in reality cannot be seen at such speeds. This is why we have tracer rounds. A very minor detail, but it could add to the suspense as it will be harder to identify where certain shots came from. Please consider this one.
- Make muzzle flashes occasional. Muzzle flashes do not occur every time the gun is fired, it's only in certain conditions when it happens. Though it is still VERY common, it could add to the gameplay a little bit. For example, if you're shooting in a dark building, the muzzle flash may light up the room for a split second revealing the enemies inside, but this tactic should not be relied on, as a muzzle flash may not occur and the room will still be kept dark, and the enemies will still be concealed in the dark. I mention this because I assume this is another factor that may have assisted or otherwise disadvantaged the soldiers in the battle.