Well, as many speculated, the URSA Broadcast G2 has now been announced:
https://www.blackmagicdesign.com/produc ... abroadcastIt sounds like Blackmagic had issues with parts availability for the sensors used in the original URSA Broadcast cameras, so apparently they have switched to using the sensor from the Pocket Cinema Camera 6K. As that sensor is a more modern design than the original, the claim is that it delivers better low light performance and dynamic range.
The sensor is a native Super35/APS-C sized sensor and allows for 6K recording when used with the EF mount. When using the B4 mount, you are limited to a 4K Ultra HD crop of the sensor. But even a 3840x2160 crop is larger than a standard 2/3-inch sensor area, so I assume that lens expander optics are built into the B4 mount (which was also the case with the original URSA Broadcast).
From what I can gather from the sensor dimensions and resolution, roughly a 1.5x expander would be needed to cover the 4K imaging area of the new sensor, which has an imaging diagonal of about 16.55mm, or slightly larger than a 1-inch sensor (the original URSA Broadcast had a Super 16 sensor with about a 15mm diagonal requiring about a 1.35x expander). So I would guess that this new camera may be a bit more demanding on lens optics, at least at 4K resolutions.