It is and it isn't. My point is that back then it wasn't possible to update software continuously. Thus, the development model was very much focused around putting out discrete, fully functional versions.

Today that isn't the case. It's all about continuous rollover. So in 20 years the software that "survived" will be the same old software that we're talking about now (from the 90s and earlier). All of the present-day software will be continually updated and may be unrecognizable in 20 years.