The next medium format camera from Fujifilm is expected to offer an even higher resolution than the expensive Phase One XF IQ4. According to the latest rumors from a reliable source, Fujifilm is currently developing a GFX camera with a 180MP medium format sensor.
Most “lossless” compressions (e.g. PNG) wouldn’t work here, because they throw away a lot of extra data you get raw from the camera sensor. Hence photographers using their camera’s “raw” file type to retain as much data as possible. A PNG may capture everything you as a consumer sees in an image, but raw file types will retain extra information you can use when editing a photo.