Three-year-old models aren't useful because there are (1) cheaper models that are roughly equivalent, and (2) better models.

If Sonnet 4.6 is actually "good enough" in some respects, maybe the models will just get cheaper along one branch, while they get better on a different branch.

It's funny, it sure seems like software projects in general follow the Lindy effect: considering their age and mindshare, I can safely predict gcc, emacs, SQLite, and Python will still be running somewhere ten, 20, 30 years from now. Indeed, people will choose to use certain software specifically because it's been around forever; it's tried and true.

But LLMs, and AI-related tooling, seem to really buck that trend: they're obsoleted almost as soon as they're released.