According to SonyRumors.CO, Sigma will have a new product announcement on July 11th, 2019. Sigma will announce their new E-mount zoom lenses for Sony APS-C mirrorless cameras and full frame mirrorless cameras.
As same as current Sigma E-mount prime lenses, these Sigma E-mount zoom lenses will have similar design as current EF-mount/F-mount lenses. Stay tuned for more info.
There is also a chance that Sigma will announce new zoom lenses designed exclusively for Sony mirrorless cameras, as Sigma CEO already confirmed before.