Increasingly, new technology has unexpected impacts on older technology. Case in point is the difficulty in getting parts for equipment so old that the parts are no longer made. If you really wanted to keep the ship, aircraft, vehicle or whatever in service, you often had to reverse-engineer the part, and have it made from scratch. Very expensive, and time consuming. That has changed over the last few years with the use of laser scanning. This allows the precise specifications for parts to be generated (from an existing part) in hours, instead of months. New manufacturing techniques, often using lasers as well, make it easier, and cheaper, to build the parts. Especially with aircraft and warships, these technologies mean much longer service life. Many new technologies are electronic, which means you can simply replace older technology, with much better (often lighter and cheaper as well) in a ship or aircraft. The B-52, in service, and much demand, for a half-century, is an extreme example. But not the only one. This is all changing the economics of procurement. It’s no longer necessary to build all new ships and warplanes to take advantage of new technologies. This is a trend that will probably continue for a while.