I want my paid-off cameras to keep working.
Yup exactly, this is the point I was trying to make. When your camera does eventually fail, you want to buy a new one that will pay itself off. Right now, that's a tricky situation as the mainline production cameras from Arri, Sony, Canon, are all half a decade old or more.
So the question becomes, does it make sense to reinvest your cash in an older model camera (something released in 2014), or try to keep the wheels moving on a camera that is on the verge of death?