I still run film, B&W since I do my own developing and the color process is a pita. I have a bunch of film in my freezer, since I have no idea when they are going to stop producing it. LargeSense just launched (July, 2021) the first full-size digital back for 4X5 view cameras for $26,000. It’s a monochrome sensor, i.e. only good for black and white. For color your best bet is a Hasselblad H6D-100c Digital Back, which you can use with a special mount on a 4X5. It’s close to a full 6X4.5 medium format (the sensor is 53.4X40.0 mm). The only reason for running it on your view camera is to take advantage of the camera’s rise and fall, shift, tilt and swing movements (really useful in architectural shoots). The back runs $26,000 and the special mounts go for about $760. Needless to say I’m sticking with B&W film for my view camera. For color I just run Canon EOS digital. At this point the image from a good digital camera is almost indistinguishable from film until you enlarge it to a ridiculous degree. However, in black and white a 4X5 or 8X10 contact print is still, to my eyes, unbeatable.
I still have an “instant film” back, but no one is making 4X5 instant film anymore (though you can still find some on e-bay), and I’ve used up my supply (no such thing as reloading for instant film). So it does make it more challenging when shooting out in the field since you don’t really know what you’ve got until you get home and develop it. Though with the new multifunction light meters, it is a bit easier to get the exposure correct. You still have to rely on the ground glass back for your composition.