The new system seems to be less complex, in terms of the number of components involved. No body sensor, no string sensor, no humbucking coil and no string ground (or, at least, there wasn't one mentioned in the operating instruction pdf). The discrete pre-amp has been replaced by a 'professional audio' grade one, with a phase switch, which visually appears to be the same pre-amp being used on the ES-T.
If the allen screws provide adjustment of the 'side-load' on the piezo elements, it seems that it might have been possible, with a little more work, to have the set screws placed in the bottom edge of the bridge between the bridge pin holes, not unlike the position of the ball end holes on a pinless bridge.
If the system is significantly more expensive to produce (initially, it may be) and more labor intensive to install (more time involved to set the pick up balance, which is doubtful), I can see it being offered on the 500/up Series when/if it is released to standard production models. I would figure that a fair number of iterations and prototypes were released to artists for their feedback to see how it performs live and in the studio, so it will be up to the general guitar buying public to decide if they like the new system better than the old.
Eventually, it would make the most sense, production-wise, to have the NES in the all solid wood models, the ES-T in the solid top models and enough parts to service the current version of ES (are there still parts, such as 2AA power supply and defeatable dual body sensor pre-amps, available for the previous versions ? )
Hoping to hear a comparison recording or to try one out at a local dealer. Maybe a updating/revision of the piezo design is what most players feel is the expected tone when an acoustic guitar is plugged in. Only time will tell.