no/limited impact
At launch its enthusiasts. Regardless of price you aren't getting mass market in - they only bought XB1S a couple years ago so aren't in the market for a new console yet.
So xbox fans will buy xbox, Sony fans will buy playstation. If Playstation is expensive, PS fans may wait for a price drop, I doubt they'd buy a series S. especially at launch where the lineup isn't really much different from current gen, just in higher quality.
XSS feels more like a way to get Xbox owners to convert across quickly, build an addressable market for gamepass as fast as possible because you know playstation will likely sell more boxes overall so that initial momentum is important. And its smart to target the likely majority of homes that have 1080p TVs with a cost-engineered box designed for that as a target