Problem with any non-mass-produced camera seems currently the availability of image sensors. It seems that the only small-batch available sensors are for machine-vision and accordingly priced :/ The CMV12000 used here costs $2000-$2200 per sensor - more than many full-frame mirrorless cameras.
Another problem is that there are no development boards as far as I'm aware. That's why this imo could be huge for anyone else interested in making an open camera, the apertus project seems to have a modular architecture and breakout board for components!
That said, the sensor does have a globoal shutter which would be huge for cinema but not sure at what tradeoffs in dynamic range or color-depth eg.