Regardless of how fast you can put data into RAM---your CPU and GPU still have to take some amount of time to use that data to build the game world and rendering pipeline. So, even with the very best PCI-e 4.0 SSD, top end CPU and GPU and RAM----there would have to be some sort of transitional screen.Ah, for some reason I was remembering Gen 3 speeds topping out at 1.5 GB/s instead of 3.5GB/s.
If they got rid of the animated transition when loading a game it would go further than updating to 1.1, probably. In robbiekhan's video that transition looked like a fixed animation rather than hiding loading. Maybe it was put there for the PS5's sake.
*watching robbiekhan load into the game in that video, was pretty incredible. I wasn't ready for how quickly it became playable!