With the mid-gen refreshes that "generational leap" is a bit complicated... they'd have to wait a decent while before they could vastly outperform the Xbox 1 X while maintaining affordability.
PS5 games will be made from the ground up for that system, the Pro/X doesn't have that luxury. So even if it's only twice as fast (12 TFLOPS), games will look much better because they don't have to work on the last gen systems.
Look at GoW on base PS4, vs the Pro. They are identical in all ways but resolution yet GoW is one of the best looking games ever made. In an age of 20+ TFLOP SLI PC's. A game optimized to look like that on a 1.8 TFLOP console. So imagine a game that uses 12 TFLOPS to the same degree? That's where the generational leap will come from.