Life expectancy of tube components

Just out of curiousity how much time can we expect to get out of a piece of tube gear. I am sure there have been many threads addressing this, but I didn't find one in my search. So for that I appologize upfront. So the question is: other than tubes, how many years can we expect to get
before other parts fail? I realize this will be brand dependant so lets say, BAT, McIntosh, Audio Research as examples of price point.