Sony is expected to announce the long awaited Sony a9 II in late October, 2019. Just ahead of PhotoPlus EXPO on October 24-26th. The Sony a9 II will compete with Canon EOS-1D X Mark III and Nikon D6 with some game changer features.
While the Sony a7S III could not coming anytime sooner, because Sony currently only has one new camera code got registered. At least we should wait another two or three months before a7S III announcement, maybe Sony will announce this camera in early 2020 ? Stay tuned.