The upcoming improved Z bodies will carry a "II" rather than an "S" designation. Sign up for news via the following link if you're interested:
https://www.nikonusa.com/en/nikon-products/zcountdown.page?signedup=true#si-nkn-sign-up-form
https://www.nikonusa.com/en/nikon-products/zcountdown.page?signedup=true#si-nkn-sign-up-form