According to latest rumors from NR, one of the upcoming TBA lenses in the Nikon Z mount lens roadmap is the NIKKOR Z 70-200mm f/4 Lens. This lens will be cheaper and lighter than NIKKOR Z 70-200mm f/2.8 S lens. Release date for this lens is in 2020 to 2021.
Nikon is rumored to announce a new APS-C (DX format) Z-mount mirrorless camera this year. Both Canon and Sony have APS-C mirrorless cameras on the market, while Nikon’s 1 series DX mirrorless cameras have been discontinued.
As Nikon Z7 full frame mirrorless camera now already released, Sigma USA just issued a press release that their Nikon F-mount lenses has no issue with general operation when they are used on the Nikon Z7 and FTZ adapter. Sigma didn’t say anything whether they will release native Z-mount lenses in near future.