Who knows? They may use another type of keyboard with aftertouch, from another product?
The original Tyros wasn't made in Japan, and used an initial/aftertouch keyboard that was not quite the same quality as those that followed on the Tyros2 etc.
It was still pretty good...maybe that one will find it's way into a S-series?
Ian
_________________________
Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.