I highly doubt it will work the way they are thinking cause games that will be built around using the SSD will be hitting it hard with I/O and transfer rates which won't leave enough room for it to be used as additional Vram and not to mention the latency issues. On top of that, the transfer rate differences and etc.
There might be examples of GPUs running into Vram problems when they are being used in production workloads but I don't watch those kinds of videos to remember. The closest thing I remember watching is when GN tested a compile benchmark with the AMD Threadripper TR 3990X with 32GB of RAM vs 64GB. Their compile benchmark ran out of 32GB of system ram due to the 64 cores so it reverted to using the SATA SSD they use which killed the CPU's performance. When they put in 64GB, it went back to being on top. While not directly the same thing, I would suspect a similar case if they used the super fast SSD for Vram.
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850
