I saw a fesw post from you Jonathan and dug around until I found this thread. Welcome back!
Cameras can die long before their wearout life. I had a shutter go on a 1DS2 at ~10,000 and a button fall off on a 1Ds3 at only a few thousand. I don't know how long parts will be around for the 1ds but as you say, just keep it until it dies ...