Let's not assume that the sensor is of a standard Micro Four Thirds size (18mm x 13.5mm).
We are assuming this new camera was designed with Black Magic Design, so let's look at their drone product, the
Black Magic Micro Cinema Camera. While that camera has a Micro Four Thirds lens mount, its sensor is of the Super 16 size (12.48mm x 7.02mm). Much much much larger than the Inspire 1's sensor (6.17mm x 4.55mm), but not a full MFT sensor. A comparison of total sensor area:
Inspire 1: 28.07 square millimeters
Super 16: 87.61 square millimeters
MFT: 243 square millimeters
So a Super 16 sensor would be three times the size of our current sensor, while a full MFT sensor would be about 8.5 times the size of our current sensor.
I would call a Super 16 sensor "large enough", and given it was designed by Black Magic Design, "the best sensor we can expect to carry on an Inspire 1". Anything larger would require an S900, I think.
Gimme gimme!