I remain sceptical. I think it's very strange for multiple people from multiple companies to "accidentally" refer to this project in a way that strongly implies Warhead at least is getting a Remaster. ("Original game's singleplayer campaigns", "these games", etc.) All that said, even if the remaster is just Crysis with a question mark over the future, I hope that they backport the Ceph AI from Warhead to the original game. They were much more dynamic in Warhead.
It depends on what you mean by "moved on". Crysis is the product of a somewhat dead gaming philosophy where immersion, reactivity, interactivity, and complexity were king. In the 2000s, PC-oriented developers were shooting for the moon.
In the FPS space, there is no modern equivalent to classic Rainbow 6. There is no modern equivalent to Crysis. Everything is simplified, everything is nailed down, everything is afraid of alienating casual players.
The reason people are excited for STALKER 2 is because they want modern games that are as good as games used to be. Metro is fun, but it just doesn't cut it. People loved Prey because it felt like System Shock 2, compared to the simplified BioShock. BioShock was the product of focus testing with people who could not handle a proper immersive sim. The devs just kept removing features until they could handle it. But Prey plays like something from the good old days. 2000-2007 had some peak videogame design, and by and large it's been downhill from there. There have been QoL improvements that are welcome, but games got a whole less TACTICAL.
One of the things about Crysis is that it's a very tactical game. You have these tools, and the nanosuit has these different modes with cost/benefit tradeoffs. So each situation calls for you to scope it out with binocs and think about how to best deal with it. One of the big tell-tale signs that something is wrong with modern Far Cry is how scoping out outposts with your binocs is largely unnecessary. In FC1, knowing where everyone was in an outpost was life or death. Modern Far Cry has extremely forgiving difficulty. They paste on all these mechanics like crafting and leveling to distract you from the fact that the actual gameplay has gotten a lot shallower, a lot less reactive.
What do Crysis fans want from Crysis 4? To a large degree, they want to wind the clock back. Discard the years of contemporary AAA fluff, and go back to how games used to be.
Part of the appeal of Crytek's Hunt: Showdown is that it places an emphasis on stuff most contemporaries don't. It's pretty hardcore, even with the changes Crytek have made to try to widen its appeal. It has extremely complex sound design including things like stepping on branches making loud snapping noises that can be heard by other players. The recent patch introduced gunshots causing your ears to ring. Its environment is non-destructible, but that's an MP design issue more than anything else. When you look at Hunt, you see a style of game that fell from favor because publishers wanted something that played like Halo, or like Call of Duty. Or played like all the super janky Battle Royale games.
Crytek games are historically about using technology to create more immersive game experiences. Crytek's definition of immersive in the Crysis 1 days centered on things like the environment reacting. You shoot a leafy plant, and the leaves whip around. You throw a man into a hut, and the hut collapses. Crysis 1 is scripted so that when you shoot a car fuel can, and the car goes up in flames and then explodes, a tire will typically bounce in your general direction. And that is a nice little art touch that truly sells that you are GOD in this domain and the world WILL OBEY YOUR EVERY WHIM. If you want to cut down all the palm trees, nobody can stop you.
The appeal of Crysis and Prey have a fair bit of overlap. And it's a curious coincidence Prey is a CryEngine game. If I want to pick up every cup and place them in a pile, and then fire a missile launcher into that pile so the cups tank the physics engine, your game must allow that. If your game stops me, your game is bad and you should feel bad for making it.
Most modern FPS games are flat, non-reactive, sterile affairs. The open world games are even worse in this regard because they go for scale over depth. To Crytek, it really mattered that you could chop down palm trees. But it's not a design priority to Ubisoft. Nor pretty much any other big AAA developer.
That's why the Xbox 360 port of Crysis 1 has better physics and reactivity than Far Cry 5. Because physics and reactivity were not a core design priority for Ubisoft. An obsession with physics and reactivity is a product of old school PC gaming sensibilities. The sensibilities that gave us Jurassic Park: Trespasser. Ubisoft's version of Trespasser is basically King Kong. Which is a really cool game, but glaringly simplified for a very mainstream audience. Trespasser was janky and frustrating, but what people want is all that ambition and complexity in a polished package. They don't want the complex baby thrown out with the janky bathwater.