Recently, some fake news websites consider a Nikon design patent that could be high-end Nikon Z9 with built-in battery grip. NikonRumors exposed that this design patent is for Nikon Z6 & Z7 with a grip.
As already rumored before, Nikon Z9 will have similar specs and feature to upcoming Nikon D6 DSLR camera. Nikon Z9 is expected to be announced in 2020. To compete with upcoming Sony a9 II and Canon EOS R Pro.