What I've observed is that programming languages have significantly caught up with the math behind them. And it's not uncommon for some of the nearly-cutting-ed

What I've observed is that programming languages have significantly caught up with the math behind them. And it's not uncommon for some of the nearly-cutting-edge math to be hundreds of years old, or more. I recently looked into algorithms for finding the GCD of two numbers, and Euclid's algorithm from 300 BC is still basically the best way to do it (with an optimization for our binary representation happening in 1967). As programming languages catch up to the underlying mathematical theory, they're going to start progressing at the pace of math breakthroughs. That kinda sounds like a good thing to me. I don't see object-oriented languages as the pinnacle. Notably missing from your list are functional languages, which I also don't see as the pinnacle, but rather "beside" OO langs. A 5GL to me is one that incorporates the best of each paradigm. I generally program in C# and TypeScript, and I'm constantly switching between an imperative style, an OO style, and a functional style. C# is almost my ideal language; its type system is just a little too weak. Perhaps it's a 4.5G language. But let's look at what you can do with it: * Strong OO support * First-class functions (functions-as-data) * Strong support for reflection, allowing powerful IoC and types-as-data * Good generic type support (reified! Yay!) * Generators with yield * Async/await flow programming, including "yield async" mixing the two * Low-level bit manipulation, arrays of structs (certain memory guarantees), unchecked operations when you need them, and other C-style concepts * LISP-style macro manipulation (code-as-data) using Expressions (under-appreciated IMO) * No higher-kinded types :( * LINQ, if you're into it ... but I prefer fluent because it's more extensible and language-idiomatic (although you can write your own limited LINQ-style methods) Add in higher-kinded types and how could you not call that a 5GL? I honestly don't know what else you could possibly want from a programming language, except maybe Rust's borrow checking (which frankly is a recent breakthrough in computer programming, kinda challenging the premise of this whole thing). My next big idea is a programming language whose type system is written with the "same sauce" as the language itself. So the output of a "program" could be the type system for another program. You could write your software in "tiers" of progressively more strict/knowledgeable type systems. That's one thing I haven't seen before that sounds neat, but who knows if it's actually useful.