It's going to be a beast, it's going to be much more powerful than a PS4 Pro, but I doubt it will be a generational leap. Also, remember the leap between PS3 and PS4 being smaller than then one between PS2 and PS3 (which was smaller than PSX to PS2 and 16bit to 32bit)? This is gonna be smaller than that.
If you think that the difference between OG PS4 and Xbox One isn't that big (with PS4 being roughly 40% faster), it's going to be pretty much the same situation between the two. Scorpio is going to aim for higher resolutions, but it doesn't have the power to do Horizon/UC4 in native 4K. Of course the use of checkerboard 2160p would allow to make games with better IQ, but are developers going to bother?
The CPU is what could make things different and give gamers 60fps versions of games that are 30fps on the Pro, but that sounds unlikely...