They don't need 3D cache... they just need to increase the CPU cache from the 8MB its currently at to 12-16MB. That coupled with a CPU upclock would give them the headroom they need to take current 30fps games on the PS5 (that internally probably average 40fps to have that 30fps fixed output) up to 60fps. The fact that the GPU would also be more powerful and that they have more overall system bandwidth will also help with this.
I think I have said it to you many times, you need to try and understand exactly what the PS5pro would be trying to do. This is not like the PS4 vs. PS4 Pro, where they were taking 1080p games and trying to output them at 4KCBR or even native 4K. Now, this is taking the exact same PS5 game code, the same resolution, textures, geometry, same everything... and just running them at higher framerates. Thats it. So you take games running at 1440p then reconstructed to 4K@30fps and make those, 1440p reconstructed to 4K@60fps. You take games currently running at 4K DRS and at up to 40fps and make them 60fps. Then you take those same games and what is their current 60fps performance modes, and take that up to as close to 120fps as possible.
Every leak or reference about this console suggests this is the strategy they are taking. So the best advice I can give is rather than dream up what your dream spec maybe then imagine what they can do with it, instead accept that they are just trying to take the same PS5 games from 30-60fps in quality mode, and the performance mode from 60 to 120fps with a little more polish here and there. And ask yourself what kinda hardware tweaks they need to accomplish that.