For those interested
TLDW; According to Digital Foundry Neural Radiance Cache and DLSS 3.5 Ray Reconstruction are not related as I thought. The descriptions for how NRC works over the last couple of years did sound close to what DLSS 3.5 is doing, but apparently not. One key difference between that comes to mind is that RR comes trained on a number of offline rendering situations and it's integrated with the next step of DLSR to reference five data sets from the game world while NRC is said to have no pre-training. One thing they seems to misspeak to is NRD vs other nvidia denoisers. NRD is more of a catchall, and depending on the RT shaders used by the game the actual denoising algorithm will change.
For Path Tracing in 2077 Nvidia reLAX is used, for Hybrid RT it's reBLUR(unless that changed at some point).
Perhaps this gives us an idea of what DLSS 4.0 may be whenever it comes out.