Ray Tracing isn't new. And with the current performance and implementation we've seen (very limited), it effectively still is as useless as it was 5 or 10 years ago. Nothing's changed, but Nvidia would love you to believe otherwise. Its comparable to VR right now: you can get some idea of the experience it should have been, but it really isn't there yet and comes at the cost of performance and quality of life. VR is another such tech that has been launched and re-launched a couple times but just won't stick because of its gross inefficiency.
Aren't we mixing 2 things here? Or maybe 3?
1)
Ray tracing (RT) is a basic rendering technique. It's been around for decades and is
fundamental - not useless or unusable as one of AMD fanboys claims.
2)
Real-time ray tracing (RTRT) is... RT in real time ;-), i.e. fast enough (whatever that means).
It's been around for a while, but used for previews - not final renders. Previews are greatly simplified - they ignore some materials and some effects. Also the resulting live render is usually low-res and under 30fps.
3)
RTRT in games means it has to be efficient enough for processing all effects, at high-resolution (1080p+) and high frequency ( has to be acceptable for gaming, i.e at maybe 1080@60fps, maybe 4K@30fps...
Honestly, RT is fár, far away still. Implementation within DX12 is not going to take off either, contrary to what some may believe or say. This needs 10+ years to mature and it needs much faster and better hardware still, plus widespread adoption.
You're talking about general processing implementation, i.e. what standard GPU cores do.
Nvidia used an ASIC and it's just way faster - just like tensor cores are way faster for neural networks.
Everything else you've said is more or less correct.
If one wants to combine RTRT with 4K@60fps, then doing that on GPGPU is 10 years away from now. But on ASIC it should be possible withing 1-2 generations, i.e. 4 years tops.
But thanks to RTX cards, you don't have to wait 10 years. For mere $1200
you can already make your games look as if it's 2028 (just at 1440p tops).
And when you buy your next RTX card in 2021 for another $1200, it should be OK for 4K@60fps.
There's just no way around it. AMD will have to respond with a similar tech, ignore RTRT ("Who needs realism? We're so romantic!") or magically make Navi 4x faster than Vega.