@Anonymous Hi, I take your point that people use cracked versions of software, even a few businesses - although in my experience of 20 years in the media industry, this is extremely rare and never involved Autodesk products that I can remember.
Anyway, my main point was: I can't imagine anyone that uses cracked software bothering with any version more than a couple of years out of date. Why would you install 2015 or older, when a cracked version of 2021 is sat there? I'm not even sure its possible to find cracked versions of 2015 today (I haven't looked, and don't recommend anybody tries!).
Assuming pirates only want the latest software, why not do the decent thing and allow an engineer/stock activation code that would be confidentially supplied to affected customers, that would enable them to activate their perpetual licenses in perpetuity, and be done with it. Problem solved. Customers with legacy licenses are happy, current subscribers are happy, and pirates won't care or notice the difference. Nobody with any serious interest in Autodesk products would bat an eyelid. By their own admission, current software uses a completely different activation system.
Given Autodesk's hands are seemingly tied by their legacy activation software vendor (I suspect a likely tale, based on a grain of truth), it is the only honourable course of action. As things stand, they are abandoning the customers that helped build Autodesk into the company it is today.
The reason why they won't do this might be because there is a chance that a proportion of customers with legacy perpetuals will switch to rental. If this is the case, they are literally scraping the bottom of the barrel.