It's incredible how Arthur C Clarke foresaw the downsides of full codebase rewrites and putting all organizational weight behind untested and cutting edge technologies all the way back in 1951. Truly prescient sci-fi writing.
Another organisation I know of replaced its "old" .net desktop client with a nice shiny Microsoft derived web solution using some customised COTs and it would solve all their maintenance issues. Sigh its a disaster as expected made all the worse because they fired the developers before the switch was even really done.
Over and over this mistake is made to rewrite and replace instead of refactor on the assumption the old code is crufty rather than battle hardened and that writing new code is easier than editing old. Never do these organisations learn to develop more maintenance friendly systems along the way.