If a language design is timeless, it means that the design is exceptionally good and stands the test of time. It means it has served everybody's needs well enough to warrant continue using it indefinitely. There is no reason why it should be relegated to retro computing.

Look at Smalltalk, for example. It's a perfect illustration of what I'm talking about. Throughout the last 50 years, it has not needed to change syntactically (except for special circumstances). It has remained true to its roots...simple, elegant, easy to learn, flexible, versatile, productive.

Today, Smalltalk is as fresh as it was in 1981 when it broke onto the cover of BYTE magazine. It still has a vibrant community of devotees. There are still three major Smalltalk vendors.

Smalltalk is classic, timeless, beautiful, powerful and good for nearly every application domain (web, machine learning, IoT, industrial control, VR, etc.). I have never found a perfect programming language but no other language could come closer than Smalltalk.