After the announcement of Sony a7R IV(B&H Photo Video/Adorama/Amazon), Sony currently still have 3 unannounced camera codes registered. One of these unannounced camera should be upcoming a9 II. The official announcement is expected in late 2019.
A new series of Sony full frame CMOS sensors now leaked on the web. These image sensors are all full frame sensors: IMX311, IMX313, IMX409, IMX521, IMX554.