Unsure - When havoc physics (for example) came on the scene, the usual hype curve of adoption played out where there were were super gimmicky games that required it and relied entirely on game mechanics being pegged around the physics capabilities. It was a short-lived phenomenon. But, today, having that kind of physics engine and capabilities is part of a toolkit that developers draw upon, and many consumers expect to be included, rather than being a single central focus.

I'm predicting this will be the same kind of story playing out again - One vendor kicks it off, some 'demo' games that build heavily on it drop but are quite short-lived, and the tech slowly turns into a commodity feature with in-game settings menu 'on/off' selectors, followed eventually by ubiquitous support to the point that nobody really talks about it any more, it's just part of 'modern graphics'.

Shaders is another good example that followed that kind of pattern, it was all the shit in the late 90s that Q3 had 'shaders', now it's not even a bullet point for most releases, but it's certainly there.

I've rambled, but my point is that I'm not sure a lynchpin 'RTX required' game is needed at all to drive industry-wide adoption here.

Sounds interesting. An interesting difference between RTX and the previous techniques is that ray tracing is needed for modern film rendering. It just doesn't make sense that movies are still rendered with CPUs and not a more parallel architecture, so it feels for me that games are just a secondary for NVIDIA for the current version of the card.

No, I really think the situation is better than that. If you view the ray tracing as "something extra", almost like when shaders were first "invented". You use them to add softer shadows. Caustics. Interesting volumetric tricks. And people will just want them.