Tamron recently has teased four new FE lenses coming soon. The telephoto zoom FE lens will be Tamron 70-180mm f/2.8 Di III RXD lens according to rumors on the web.
This Tamron 70-180mm f/2.8 Di III RXD lens will be a very compact lightweight lens compared to Sony FE 70-200mm f/2.8 GM OSS Lens. The official announcement is expected in October, 2019. Stay tuned.