I don't think there's any general law for whether they do or don't.
On one hand, I can definitely look at C# right now and see how it is a vast improvement upon C# 1.0. I'll even go as far as to say I would probably refuse to write code in C# if it had not become what it is today.
On the other, I think you can only really change a language up to a certain degree before creating an inconsistent mess. If trends in the future dictate the need for a shift in paradigms, the extent to which existing languages can accommodate this shift is probably limited. I mean, you can often incorporate features that are based on the new approach to thinking about a problem, but once you start changing the core semantics of the language you're probably going to be better off with something completely new.
On one hand, I can definitely look at C# right now and see how it is a vast improvement upon C# 1.0. I'll even go as far as to say I would probably refuse to write code in C# if it had not become what it is today.
On the other, I think you can only really change a language up to a certain degree before creating an inconsistent mess. If trends in the future dictate the need for a shift in paradigms, the extent to which existing languages can accommodate this shift is probably limited. I mean, you can often incorporate features that are based on the new approach to thinking about a problem, but once you start changing the core semantics of the language you're probably going to be better off with something completely new.