Imagine if you had active equipment in your network that was first produced in 1952, the last ones were built in 1964, and you didn't expect to retire them until at least 2040, because none of the intended replacements had worked out.
http://www.nytimes.com/2015/12/06/us/b-52s-us-air-force-bombers.html https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress
