I think they need to take a break. They overflooded the shooter market with the same thing over and over and over and over and over and over to the point that the FPS market is so high in concentration with that games that more than just mimic each other, they outright copy/paste each other with a different color scheme and visual appearance (And let's be honest, even that doesn't change that much). And now that CoD has become heavily micro-transaction based it's no longer the fun, competitive shooter it used to be. It's a CS:GO rehash for consoles. Activision brought this. Not Infinity Ward, not Sledgehammer, and most definitely not Treyarch. Call of Duty is Activision's and pretty much the FPS genre's flagship title. However, Battlefield finally took the throne this year for the genre with Battlefield 1.
This is a perfect time for them to look back and see where they went wrong. If they really looked at their sales enough to care, they would notice that after Ghosts, sales dramatically dropped. Hell, Ghosts itself didn't sell as well as Black Ops II did, which still holds the title as the second best selling CoD of all time, right behind Black Ops 1, which holds the title of the best selling Xbox 360 game ever, with over 12 million copies sold as of 2015.
This should be a good enough sign to them that it's time to take a break. When the release of your trailer for your newest game in the best selling video game franchise in the last decade becomes the second most disliked video on youtube within the first week of being uploaded (Holding the title of the fastest disliked video ever), something is wrong. When you lose the old players of the game and grab the attention of the younger children who access to their parents credit cards and run them like crazy, something is wrong. That is not what CoD is supposed to be. They can say that those kids shouldn't be playing the game because it's rated M, but who in gods name actually reads those things. Technically someone under 17 isn't supposed to be able to buy rated M games, and anyone under 13 isn't supposed to be able to buy rated T games, but in reality in a 9 year old can walk in and buy GTAV or MKX (Considered the most violent games ever mass-produced), walk home, and play them. Now I don't personally think it's a bad thing, but it removes one of the only defenses that Activision could have to defend their decision making in the series.
I don't think the three developers are the issue, either. All three are very well rounded developers in their own respect, but when you throw big daddy Activision in the mix, you get your games ruined. Look at Destiny, for example. One of the highest potential games EVER, ruined because Activision shoved their greedy noses into it and forced Bungie to release DLC when they didn't want to yet. They forced them to make micro-transactions (Thank god they weren't p2w items and were purely cosmetic, but the fact that paying is the ONLY way to get some of the best looking things in the game is messed up in my opinion). If Bungie had been left alone with this project and not been forced on deadlines and required to bow to King Activision, Destiny would have been an amazing game (Personally, I still love it for what it is. I think it's a respectable attempt under the fire of Activision).
If they just take a break, learn from their mistakes, and come back with a large, unified attempt at a Call of Duty game and stop the yearly releases, they could make a come back. As for now though, Call of Duty is dead. Infinite Warfare may be labeled a CoD game, but it isn't. Neither is Black Ops 3 or Advanced Warfare. Black Ops 3 wasn't awful, though. It was respectable, but it wasn't Call of Duty. Ghosts was the last true CoD game, and Black Ops II was the last good CoD game (In my opinion).