The Nikon NIKKOR Z 400mm f/2.8 TC VR S mirrorless lens for Z-mount is coming soon - Nikon Rumors
Re: Nikon 400mm F2.8 - non VR version: Nikon SLR Lens Talk Forum: Digital Photography Review
Nikon is developing the NIKKOR Z 400mm f/2.8 TC VR S super-telephoto prime lens with a built-in 1.4x teleconverter for the Nikon Z mount system – Product News - Nikon Hong Kong