There's no "language to rule them all". Java already tried and almost ruled the world, but reality is that with options languages take here and there to whats important to them, they will never expand to a certain level.
Languages compete in their axes, which for me there are mainly 4 big ones:
a) System/Performance/Control: C, C++, Rust, Zig
b) Application: Java, C#, Swift, Go, Kotlin, Nim
c) Script/Casual: Python, Ruby, Lua, Javascript
d) Domain specific: OCAML, Scheme, Haskell, Matlab
I've never seen a language ruling in two axes at the same time (as in you can use it for the same goals), let alone in all four, or at least three.
The a' axis are very hardcore languages with insane amount of control, but they will never be as productive as the b' and c' axis.
Meanwhile the b' axis is the most popular one, as they allow you to create big and complex application while being productive. Their runtime are not far away from the languages on the a' axis.
The c' axis is most productive and easy to pick up, with languages that feels more natural, but they dont have the performance of the a' and b' axis and also its hard to compose big applications on them unlike the a' and b' axis.
Maybe a successor of languages like Rust and Swift might be the on to do this, but i cant hardly see Rust in that position because programming in it have more or less the kind of productivity that C++ gives you.
I relax much more when i can write something in Swift instead of C++ or Rust for instance, and i would mostly choose it given the perfect match to the problem i'm solving.
I think we are going for a more polyglot world, not less, and i mostly use C++, Swift and Python when i can, where you can replace C++ for Rust, Swift for C# and Python with JavaScript according to your personal tastes.
But using something from one axis trying to reach for the goals better served in another axis is mostly a "when all you have is a hammer.." kind of paradox.
