In a recent interview Sigma’s CEO Kazuto Yamaki mentioned that their short-term strategy indeed involves the possibility of introducing mirrorless lenses for Nikon Z-mount (I reported that rumor last year):
“It’s true that the photography market has been systematically shrinking for years – in keeping with more and more people simply using smartphones to make photos and videos. Less cameras sold also means less potential customers interested in buying a lens, which is why our short‑term strategy indeed involves a possibility of introducing lenses with new mounts – to such photography systems as Nikon Z or Canon EOS R. So far, however, the number of orders for our lenses is still above our manufacturing capacities, and especially the capabilities of our R&D department.” (Source: ICAN)
Thanks Tomasz!