Along with new Sony full frame mirrorless camera, a new FE lens Sony FE 100-400mm G lens is rumored to be announced in April, next month. This new FE lens is currently in developing by Sony.
I heard from source that Sony is developing FE100-400G.
If development is in time, it will be announced with a new camera in April.
Price and specs of this FE 100-400mm G lens is currently unknown, stay tuned for more info.