Let's do some fun math.
My RTX 5090 can manage to play Quake 2 RTX with denoising off at 4k and deliver around 150 frames per second. Denoising is not the future it is a stop gap to make up for the lack of performance we have today.
Of those 150 frames, 0 of them are "complete." Each frame is a sporadic cluster of filled in pixels and A LOT of empty space. This is because to path trace every pixel in a 3840x2160 frame, it would take an enormous amount of processing. How much processing?
Quake 2 RTX allows you to freeze the game logic loop so everything pauses in place and you can start accumulating multiple frames worth of path traced rendering to get a fully processed frame without any denoising.
By default, the game will process 500 frames to achieve a fully rendered 3840x2160 frame free of noise. Sometimes 500 isn't enough, it can take thousands of these partially rendered frames to accumulate enough properly calculated pixels if the lighting conditions are extra demanding.
This means if we want to play Quake 2 RTX at 4k and get a solid 60 frames per second without any ugly denoising or render artifacts, we need to take 60 and multiply it by the number of frames it takes to get a single fully rendered frame which is a minimum of 500, and we get 30,000 frames per second worth of performance to play without denoising or any artifacts.
Since the 5090 can only deliver around 150 fps, we need to take 30,000 and divide it by 150 to get an idea of how much faster our imaginary future GPU needs to be in order to hit that 4k 60 mark. The result is a card that is 200x faster than an RTX 5090. For context, the RTX 5090 is only about 5x faster than a 1080 Ti in raw performance, and that GPU is 9 years old. Sure, when you start using DLSS and AI techniques you can fake your way to significantly faster performance, but it isn't true real processing power gains. It's imaginary, like frame generation.
All this and keep in mind we've been talking about Quake 2 RTX, a game with geometry and levels designed for a Pentium 1 200Mhz processor to handle with software rendering, and it isn't even a feature-complete path trace renderer as it's missing caustics which increase the processing requirements by orders of magnitude more. If a scene has caustics, you can increase that 500 frames to something absurd like 10,000 or more.
TLDR it's a pipe dream and this AI craze is to distract shareholders and the public from reality to keep line going