Sony is going to initially struggle in conveying to the average consumer what makes their SSD solution special; what it'll mean to level design, and how big of an advantage it likely is. But the average consumer may inevitably understand as the exclusives start dropping and the word spreads.
Assuming Sony will be able to deliver on their promise in concerns to the advanced boost mode, the GPU TFLOPS gap between PS5 and XSX should be more marginal than PS4 vs X1 or PS4P vs X1X. To top it off, the much higher frequency on PS4 apparently means that it'll handle certain tasks better. PS4/X1X never had a SERIOUS advantage over X1/PS4P in the first place, and yet the gap this time around is much smaller. To reiterate though, it'll all depend on whether or not the variable clockrates work as efficiently as Sony claims.
As for SSD, Sony didn't just accidentally trip over and took the wrong route; they know exactly what they're doing and why they sacrificed a bit of power for this. As far as level design, I feel that PS5 will most likely have an enormous advantage that can potentially entice quite a few third parties to start making exclusives for it. MS is also aware of the significance of a standard super fast SSD but decided to capitalize on TFLOPS hype instead, which could manifest as a slightly higher resolution and little else, honestly.
MS also didn't blindly choose the design they did, both the XBX and XSX are work of a very commited team that knows really well what they are doing.
Even if Sony deliberatedly choose that route they were outplayed by MS in a lot of ways this time.
Sony went on about the new experience (how much of that SSD, Audio system and Controller feedback can infuence games) but MS has played really well the evolution card.
Also Sony tasking AMD with PS4 BC and MS working themselves on full BC... yeah, Sony should learn from that.
Poor PS3 deserved to have its library available for more people...