> At the extreme opposite end you have things like enterprise software using subscriptions, whereby the software continues to produce value year over year, but you're generally also paying developers' salaries to maintain and enhance the softare year over year. That, too, makes little sense in spreading out salaries as a cost over 5 years.

There's also a ship-of-theseus problem here. How much change has to happen to a codebase before it's not the same software anymore?