The history of cameras has been one of modularity. Any 35mm professional camera from the 1960’s allowed you to add a grip, motor drive, different viewfinder and even bulk film backs.
Medium format and large format has always been modular and extremely flexible.
My large format camera, an Ebony 45S and my medium format Hasselblad 503CW are both old school and very modular.
The reason this post came about is that when shooting in the studio with my medium format camera, when using film I have a long lead running from the flash port on the lens to a remote unit to trigger the flash, when using my PhaseOne digital back then its a cable connected to the flash port on the back. I have the waist level viewfinder so no hot shoe.
I have been researching other viewfinders particular those with cold shoes, that way I can fit the wireless trigger in the cold shoe and run a short 10 cm cable to that and not have a longer cable running to the floor.
I find it interesting that the trend has been for less modular and less upgradable cameras since digital came along. Now that trend is moving to medium format. The first was the Leica S and the Pentax 645Z, less modular and with handling like a 35mm camera.
Now we have Hasselblad and Fuji releasing mirrorless medium format cameras and we now have a real race on to produce small cheap medium format cameras that handle like 35mm cameras. Cheap is relative as we are still looking at a near £10K investment to get you started.