The ultimate "anti-cheat" is playing on some trusted party's computer. That can be a cloud machine, but I think today a game console would work just as well, turn that closed nature into an actual user-facing benefit. Console manufacturers seem focused on their traditional niche of controller couch gaming and not on appealing to high-FPS keyboard-and-mouse gamers, though.
XIM fakes being a controller but is KBM. I sort of wonder whether it’s possible to use a camera to get a stream of the game and make an aimbot either by making a fake controller or a robot that manipulates a real controller.
True that wallhacks aren’t possible via peripherals, though. You might be able to get some level of info from the audio output and map knowledge, but nowhere near the same as true ESP.
It doesn't even seem very hard to implement, steam already has the ability to stream games, they could add this pretty easily as an option for any game (although there is the concern of the extra cost of running the servers).
That shouldn't be a problem if all players, regardless of the OS, are required to use the same cloud service with similar latency.
To be fair kernel anticheat can't block this completely either, it can be run on external hardware that uses a capture card to analyze your video feed and alter your mouse inputs to the computer. Generally undetectable unless the game is able to identify unnatural mouse movements.
I think at some point defeating this becomes impossible. This sort of cheating isn't much different conceptually from just having someone who's really good at the game play for you.
Not if only the rendering is done on the client. Look at rocket league.
Edit: of course, it is still possible to cheat in rocket league, but because all physics state is server authoritative at best a perfectly coded cheat could play like a perfect human, not supernatural.
Of course, to TFA's point on network code... a lot of the issues in question could come down to checking for movements that exceed human... moving faster than the speed in game, or even twitch aiming movements faster than a mouse, or a consistent level of X accuracy in shooting over time. On the last part, I'm not sure if there might be some way to mask a user's hit zone, rendering and such so that an aim-bot thinks the foot is center-mass, etc. Or if it could be randomly shifted in a test scenario.
It's much harder to cheat if the game isn't running on your computer.