Jaguar is dead.Shrinking it to 14nm if made will be fully paid by Sony as is not anymore in AMD roadmaps.
It's in MS's long-term interest to also have their APU on a smaller node, so there's no reason to assume Sony would be financing this alone.
What's required for raytracing to be high performance in consoles?
Is it memory bandwidth or GPU core efficiency and performance?
If PS5 goes raytracing at ~4K what does that mean for backwards compatibility?
All of the above. It's very unlikely a PS5 would have the needed power anyway.
GPU's went in a very specific direction a long time ago. It was for rendering polygons, offering programmable shaders, etc. While GPU are relatively flexible, they are still most efficient doing that sort of rendering at their core.
In that regard, ray tracing is no different from other alternative rendering methods like Voxels or NURBS. Can you do it? Sure. And some parts of the rendering pipeline can be hammered into existing acceleration, but others need brute force since it's fighting the core design of the GPU.
The reality is even with console TDP requirements we likely could get efficient ray tracing, voxels, or what-have-you. The problem is that would require the GPU to be designed from the ground up to support acceleration for that kind of rendering. So in other words, you'd have to give up the features that we're accustomed to. Worse, this would mean all devs would need to be on board. They'd have to give up all of their experience with rendering graphics in their current form and throw away all of their libraries. For game makers it would be a complete paradigm shift in graphics development. That just doesn't seem tenable.
A hybrid approach could work - were part of the GPU is dedicated to traditional rendering, and part is for something else. Even if you disregard the R&D involved in accelerating a different rendering paradigm, the problem is there are cost limitations directly tied to transistor budget. If you're dedicated some to something like ray tracing, you're taking away would could have been dedicated to traditional polygonal rendering. In other words you are limiting the capabilities for traditional graphics for the relatively small number of devs that would use the alternative. What console manufacturer would take that risk? A competitor would offer a console that crushes it for traditional rendering and eat their lunch.
Unless something major changes, I just don't see ray tracing being a major thing until it can be done well via brute force on a traditional architecture. And that's going to be a while.
One thing I could see though is some dedicated hardware for ray casting. Physics cards eventually got dedicated silicon, and I wonder if the same could happen here? It may be possible to get efficient multi-source lighting with dedicated hardware on a relatively small transistor budget. Just realize ray casting is not the same thing as full pipeline ray tracing for your rendering. It's using a similar concept but specifically for your lighting engine.
