Usable life of meters may be an improper measure. Until Roche came out with some professional models of the XS, and some models aimed specifically at home testers, the manufacturers really had no way of knowing whether their meters would be used for 26 tests a year, or 26 tests a day. They made them to run, with minimal maintenance, for probably many thousands of tests.
Roche has made the CoaguChek S and earlier models 'end of life' models by announcing that it will stop supporting and stop manufacturing test strips past October 2011.
The question may not be one of finding a meter that will last 50 years -- it'll be one of whether or not the manufacturer will still support it, and whether or not you would even WANT to use an old meter. Have you tried finding a blank VHS tape? Do you have an 8-Track tape deck or 8-Track tapes?
Over the years, we'll undoubtedly see meters changing (if not actually improving), with more features (1,000,000 test memory perhaps), and incompatibilities with earlier models. It's the way the business works.
With an always rising number of people taking Warfarin (an older population with v-fib, and an increasing number of people with man made valves, and a growing acceptance of self-testing), there will probably be new monitors every few years. The cost of the strips will probably eventually drop. The regulatory authorities may realize that there's no harm done by allowing a self tester to purchase the strips directly without a prescription, and this may reduce the price of the strips.
But the idea of a 'lifetime' meter is probably not realistic - unless you expect to have a short lifetime.