According to NR, Nikon will soon announce a new NIKKOR Z 400mm f/4.5 S lens for Nikon Z-mount mirrorless cameras. The announcement date is expected in next few days.
This new NIKKOR Z 400mm f/4.5 S lens will be a very compact mirrorless lens. And will be will be part of the Nikon S-line with very high performance.
Nikon is also rumored to announce a new APS-C Z-mount mirrorless camera soon, stay tuned for more info.