Activision's next annual money machine, Call of Duty: Modern Warfare, will heavily feature crossplay it seems. Aside from being the first entry in the series to have the feature at launch, matchmaking will be based on the input device.
Call of Duty: Modern Warfare will feature crossplay between PC, Xbox One and even PlayStation 4 even though Sony are known for putting brakes on the feature in several games. Infinity Ward didn't stop there though and decided to see crossplay through properly.
The main problem that pops with crossplay these days is the input method. No one disputes that keyboard and mouse is the superior version of input in shooter games and when it comes to fast-paced shooters like Call of Duty series, the difference would be pronounced even more.
In order to avoid giving advantage to PC players, Infinity Ward will lean on input-based matchmaking. Epic Games have pioneered the feature with their strong crossplay push via Fortnite and it seems like more companies are willing to adopt the system.
Therefore, console players will by default only enter matches with other console players, or with PC players that are using a gamepad instead of keyboard and mouse. On the other hand, if a console player parties up with a PC player, they will still get matched with keyboard and mouse players (K+M) and will enter matches with that input.
Unfortunately, the Forbes article where this info came from didn't specify whether Call of Duty: Modern Warfare will have K+M support for Xbox One or PlayStation 4. It is a safer bet to assume that it will not for the moment.
Console players who matchmake with only those who use gamepads should also be wary of other advantages other players may have. For example, if you are not a PS4 Pro or Xbox One X owner, it is highly likely you will be stuck with 30 FPS cap, which is not the case with PC or the advanced consoles.
Having a fluid gameplay experience is an advantage on its own, especially in multiplayer matches where smooth controls are crucial but it has been proven time and again that some games' mechanics depend on the frame rate. Don't be surprised if your shots stop registering if you are stuck with 30 FPS.