I'm pretty sure the whole point of RED is to disrupt companies like Panavision. I suspect people still use their cameras because that's what they were trained on, and there is significant brand loyalty in the business.

The Genesis is a digital camera that pretends to be a film camera, just like Avid is a NLE that pretends to be a film cutter.

Genesis filmography: http://en.wikipedia.org/wiki/Genesis_(camera)#Filmography

RED filmography: http://www.imdb.com/company/co0203252/