Unless Microsoft pull off something like this patents don't expect any miracle in camera department.
Because realistically think about it how big sensor Microsoft can put in 4.8 mm thin device. I think it will end up with 1/3inch sensor same size as lumia 920 sensor. Maybe by providing multiple camera like current iPhones Microsoft can achieve decent image quality.
Overall I think you can't expect as good camera as current samsung & apple phones.
Unfortunately this is the sacrifice Microsoft have to make to design both half of surface duo identically thin at 4.8 mm.