So, obviously 'never' is hyperbole on Buffett's part.

Nope, finance doesn't work like that.

I'll buy that value investing stopped working as well because of increased investor sophistication and a general increase in asset prices. As a somewhat related example, daily S&P 500 momentum investing worked up until 1980, and now you need to track more sophisticated momentum measurements. But to quote Cliff Asness (talking about momentum investing, not value investing):

If everyone did them yesterday, they would go away. They work in my opinion — again using my version of “work” — in kind of a sweet spot. Good enough to be really important if you can follow discipline, not so good enough that the world looks at it and goes, “this is easy.” They’re excruciating at times and I hate those times. I won’t pretend I’m neutral as to those times.