[bluGill]

Maybe, but most software projects isn't designed for as long as things will last (I'm not sure we even know how to do this!). It is best to think of software as under continuous remodels. Very few houses survive for 40 years without a major remodel - adding rooms, moving walls. (much less "minor remodels" like replacing the kitchen cupboards - and the paint will not last for 40 years no matter how hard you try).

If you continuously remodel your house like software is, then by the time it is 50 years old there should be zero original walls left. But software is a lot cheaper to make changes to.